MOTOR VEHICLE EXHAUST GASSING
SUICIDES IN AUSTRALIA:
EPIDEMIOLOGY AND PREVENTION
by
Virginia Routley
September, 1998
Report No. 139
Victorian Injury Surveillance & Applied Research Function
ii
MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
REPORT DOCUMENTATION PAGE
Report No.
Date
ISBN
Pages
139
September 1998
0 7326 14376
73
Title and sub-title:
Motor vehicle exhaust gassing suicides in Australia: epidemiology and prevention.
Author(s)
Type of Report & Period Covered:
Virginia Routley
GENERAL, 1994-1998
Performing Organisation(s):
Monash University Accident Research Centre, Wellington Road, Clayton, Victoria. 3168
Abstract:
Suicide is a major public health problem in Australia. In 1996 carbon monoxide poisoning from
motor vehicle exhaust gas was the second major method, accounting for almost 22% of suicides. For some
survivors there were lasting effects on the heart and brain.
The aim of the study was to reduce the overall suicide rate by making motor vehicle exhaust gas
suicide substantially more difficult to undertake and complete. Since the method is common and relatively
lethal this has high potential to reduce total suicides. The study involved a literature review and obtaining of
background information on suicide and methods of suicide, particularly exhaust gas suicide, data analysis,
personal communication with technical experts, being informed of other current or unpublished studies, an
examination of a sample of exhaust gas suicide Victorian State Coroner’s case files and an awareness of
activities to reduce the method.
Motor vehicle exhaust gas suicides have increased in rates, as a proportion of suicides and in
numbers since at least 1968, despite the introduction of catalytic converters in 1986. The method is most
commonly used by middle-aged males. Its usage varies between states and it is a relatively favoured method
in Australia compared with other countries. Hospital admissions have increased considerably in recent years,
at a faster rate than deaths. In a sample of Coroner’s records 36% of victims’ vehicles had catalytic
converters. Almost all used a hose or pipe leading into the interior of the vehicle with ventilation sealed.
They were most frequently undertaken at home or at an open-air location away from home.
While recognising that the causes of suicide are complex there are design changes which potentially
make the method more difficult to affect. These are multi-gas (CO, O2 and possibly CO2) sensing devices
installed in the vehicle cabin which emit a warning light followed by an alarm and then shut down the engine
when the levels become life threatening, exhaust modifications which make it difficult to fit a hose or pipe
and further improvements in engine design and catalytic conversion techniques.
Recommendations are for the introduction of mandatory regulations for new vehicles to ensure that
life threatening gas levels cannot be reached by passing a hose from the exhaust into the vehicle over the
lifetime of the vehicle. In-service vehicles should be required to replace existing exhaust pipes with new
safety designs to make it substantially more difficult to attach a hose. A study of exhaust gassing suicide
attempters and the Suicide Module of the National Coronial Information System should collect information
which further clarifies potential countermeasures and risk factors.
The Australian Medical Association has convened a multi-sectoral committee, on which MUARC is
represented. It is progressing research to reduce exhaust gassing suicides, relevant to the above design
changes and recommendations, with the assistance of $30,000 from the Department of Health & Family
Services.
Key Words:
suicide, exhaust gassing, carbon monoxide,
prevention
Reproduction of this page is authorised
Disclaimer
This report is disseminated in the interests
information exchange. The views expressed here
those of the authors, and not necessarily those of
Monash University Accident Research Centre or
Victorian Health Promotion Foundation.
of
are
the
the
Monash University Accident Research Centre,
Wellington Road, Clayton, Victoria, 3168, Australia.
Telephone: +61 3 9905 4371, Fax: +61 3 9905 4363
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
iii
Contents
ACKNOWLEDGMENTS .......................................................................................................VIII
EXECUTIVE SUMMARY .........................................................................................................X
GLOSSARY ........................................................................................................................ XVII
1.
INTRODUCTION .............................................................................................................. 1
1.1 Rationale......................................................................................................................................1
1.1.1 Australian Data ...................................................................................................................1
1.1.2 Potential for Prevention ......................................................................................................1
1.2 Background .................................................................................................................................1
1.3 The study .....................................................................................................................................2
1.3.1 Overview ............................................................................................................................2
1.3.2 Literature review.................................................................................................................2
1.3.3 Aim .....................................................................................................................................2
1.3.4 Objectives ...........................................................................................................................2
1.3.5 Method................................................................................................................................3
1.3.6 Results ................................................................................................................................4
1.3.7 Recommendations, Conclusions and Progress ...................................................................4
2.
LITERATURE REVIEW AND BACKGROUND INFORMATION - SUICIDE ................... 5
2.1 Suicide overview .........................................................................................................................5
2.1.1 Introduction ........................................................................................................................5
2.1.2 Suicide Patterns in Australia...............................................................................................5
2.1.3 Factors influencing suicide rates ........................................................................................6
2.2 Methods of suicide ......................................................................................................................9
2.2.1 Determinants of choice .......................................................................................................9
2.2.2 Methods used......................................................................................................................9
2.2.3 Restriction of method .......................................................................................................13
2.2.4 Transference between methods of suicide ........................................................................13
2.3 Attempted Suicides ...................................................................................................................14
3. LITERATURE REVIEW AND BACKGROUND INFORMATION - CARBON
MONOXIDE............................................................................................................................ 15
3.1 Characteristics of carbon monoxide poisoning .........................................................................15
3.2 CO Standards.............................................................................................................................17
3.3 Motor vehicle exhaust gas.........................................................................................................18
4. MOTOR VEHICLE EXHAUST GAS SUICIDES – DATA ANALYSIS AND OTHER
STUDIES................................................................................................................................ 19
4.1 Data analysis .............................................................................................................................19
4.1.1 Australian Bureau of Statistics (ABS)..............................................................................19
4.1.2 Victorian Coroners Facilitation System (CFS) 1993/94...................................................22
4.2 Victorian Coroners’ Files ..........................................................................................................23
4.3 Other studies..............................................................................................................................25
4.3.1 International Studies .........................................................................................................25
4.3.2 NSW Institute of Forensic Medicine ................................................................................26
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MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
4.3.3
4.3.4
4.3.5
National Injury Surveillance Unit ....................................................................................26
New et al, May 1996 ........................................................................................................27
Further Research...............................................................................................................27
5. IMPACT ON EXHAUST GAS SUICIDES OF ENVIRONMENTAL EMISSION
CONTROLS............................................................................................................................29
5.1 Nature of controls......................................................................................................................29
5.2 Impact of controls .....................................................................................................................29
5.2.1 Literature ..........................................................................................................................29
5.2.2 Australian data..................................................................................................................30
5.2.3 USA Data .........................................................................................................................30
5.2.4 Japanese data ....................................................................................................................32
5.3 Explanations for suicides in later model vehicles .....................................................................32
6.
PREVENTION, RECOMMENDATIONS AND PROGRESS ...........................................35
6.1 Rationale for Prevention ...........................................................................................................35
6.2 Costs and benefits .....................................................................................................................35
6.3 Design Solutions .......................................................................................................................35
6.3.1 Sensing Device .................................................................................................................35
6.3.2 Exhaust Modifications......................................................................................................36
6.3.3 Further Improvements in Engine Design..........................................................................37
6.3.4 Other.................................................................................................................................37
6.3.5 Discussion ........................................................................................................................37
6.4 Recommendations .....................................................................................................................38
6.5 Progress .....................................................................................................................................38
6.5.1 Department of Health and Family Services......................................................................38
6.5.2 Australian Medical Association (AMA)...........................................................................39
7.
REFERENCES ...............................................................................................................41
ATTACHMENT 1....................................................................................................................45
ATTACHMENT 2....................................................................................................................46
ATTACHMENT 3....................................................................................................................48
Paper for AMA convened working group to reduce motor vehicle exhaust gas suicides .................48
Cost-Effectiveness of Vehicle Exhaust Gas Suicide Countermeasures .............................................48
1.
Introduction ...............................................................................................................................48
2.
Carbon Monoxide Detectors .....................................................................................................48
2.1 Background...........................................................................................................................48
2.2 Performance Standard for CO Inside the Car .......................................................................48
2.3 Likely Effectiveness .............................................................................................................49
2.4 Time Period for Implementation...........................................................................................49
2.5 Number of Suicides Prevented..............................................................................................49
2.6 Cost of Implementation ........................................................................................................50
2.7 Cost-effectiveness.................................................................................................................50
3. Exhaust Pipe Modifications ......................................................................................................51
3.1 Performance Standard...........................................................................................................51
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
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3.2 Likely Effectiveness..............................................................................................................51
3.3 Time Period for Implementation...........................................................................................51
3.4 Number of Suicides Prevented..............................................................................................52
3.5 Cost of Implementation.........................................................................................................52
3.6 Cost-effectiveness .................................................................................................................52
4. Conclusions ...............................................................................................................................53
5.
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Acknowledgements ...................................................................................................................53
MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
Figures
FIGURE 1. SUICIDE-STANDARDIZED MORTALITY RATES AUSTRALIA 1922-92.......................................................... 6
FIGURE 2. MALE SUICIDE RATES AUSTRALIA 1922-92 BY AGE GROUP ..................................................................... 6
FIGURE 3. METHOD OF SUICIDE-AGE STANDARDIZED MORTALITY RATES AUSTRALIA 1922-92, MALES................ 10
FIGURE 4. METHOD OF SUICIDE-AGE STANDARDIZED MORTALITY RATES AUSTRALIA 1922-92, FEMALES ............ 11
FIGURE 5. MEANS OF SUICIDE AS A % OF TOTAL AUSTRALIAN SUICIDES................................................................ 12
FIGURE 6. THE TIME COURSES OF THE CONCENTRATIONS OF CARBOXYHAEMOGLOBIN IN THE MIXED VENOUS
BLOOD ON EXPOSURE TO BREATHING CO AT INSPIRED CONCENTRATIONS OF 0.01%, 0.05% AND
0.1% IN AIR, AT REST (BROKEN LINES) AND DURING LIGHT EXERCISE (SOLID LINES).......................... 16
FIGURE 7. MOTOR VEHICLE EXHAUST GAS SUICIDE AND MOTOR VEHICLE REGISTRATION RATES, AUSTRALIA.
(1971-1996) ....................................................................................................................................... 19
FIGURE 8. MOTOR VEHICLE EXHAUST GASSINGS FOR AUSTRALIA, 1970-1995 ...................................................... 20
FIGURE 9. EXHAUST GASSINGS AS A % OF ALL SUICIDES BY AGE GROUP................................................................ 21
FIGURE 10. EXHAUST GASSING SUICIDES AUSTRALIA: FREQUENCY BY AGE GROUP ............................................... 21
FIGURE 11. DEATHS AND HOSPITAL ADMISSIONS FOR MOTOR VEHICLE EXHAUST GAS SUICIDES AND SUICIDE
ATTEMPTS, AUSTRALIA, 1991-1996................................................................................................... 22
FIGURE 12. MOTOR VEHICLE EXHAUST DEATHS IN THE USA (1970-1991) ............................................................ 31
Tables
TABLE 1. METHODS OF COMPLETED SUICIDE - AUSTRALIA .................................................................................... 12
TABLE 2 SYMPTOMS INDUCED BY VARIOUS BLOOD CONCENTRATIONS OF CO (AT SEA LEVEL WITH NORMAL
HAEMOGLOBIN LEVEL) ....................................................................................................................... 17
TABLE 3. REASONS FOR MVEG SUICIDE, VICTORIA. (1993/1994) ........................................................................ 23
TABLE 4. DEATHS FROM CAR EXHAUST GASSINGS - LOCATION ............................................................................ 24
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
vii
ACKNOWLEDGMENTS
Assistance from the following individuals and organisations is greatly appreciated: Profs.
Joan Ozanne-Smith and Peter Vulcan (MUARC) for support in investigating this important
issue and undertaking related activities and for providing extensive editorial comments;
Jerry Moller (formerly National Injury Surveillance Unit, Australian Institute of Health &
Welfare) for editorial comments and helpful advice over the years of this project; Phil
Waller (Phil Waller Motors), Bob Powell, Stuart McDonald (Royal Automobile Club of
Victoria), Brian Hobsbawn (Environment Australia) and George Rechnitzer (MUARC) for
providing much needed mechanical advice; Stan Bordeaux (NISU), Dr John Langley,
Injury Prevention Research Unit, Dunedin, New Zealand, Dr Johannes Wiik, National
Institute of Public Health, Oslo, the Consumer Safety Institute, Amsterdam, Dr David
Lester, Richard Stockton State College, New Jersey, USA and Assoc. Prof Pierre Baume
(formerly AISRAP) for willingly providing data; Victorian State Coroner’s Office for
providing access to records; Assoc. Prof. David Ranson (Victorian Institute of Forensic
Medicine) for identification of cases; Alan Bruhn (Victoria Workcover Authority), Steven
Gow (formerly Hyperbaric Unit, Alfred Hospital), Dr Ella Sugo (formerly NSW Institute
of Forensic Medicine), Kirsten Cross (AMA) and Dr Ric Bouvier for helpful discussions;
Dr Ella Sugo and Dr Peter New (Hampton Rehabilitation Hospital and Caulfield General
Medical Centre) for permission to reference their unpublished studies and MUARC staff
Christine Chesterman, Voula Stathakis, Ruth Zupo and Karen Ashby for valued assistance
with data collection, data analysis, report layout and general support, respectively. To the
MUARC staff involved I have especially appreciated their patience with this evolving
project which has extended far beyond what was originally envisaged.
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MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
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EXECUTIVE SUMMARY
Suicide is a major problem in Australia. In recent years there have been approximately
2000 deaths each year from suicide. Since 1990 suicide has been more common than motor
vehicles crashes as a cause of death. In 1996 motor vehicle exhaust gas was the second
major method of suicide, accounting for almost 22% of suicides. It was the method most
commonly used by middle-aged males.
There is evidence that reduction in access to a lethal means potentially reduces the overall
suicide rate. The potential for reduction is greatest where the restricted method is
commonly used. Motor vehicle exhaust gassing fits many of these criteria.
The study
The study involved a literature review and obtaining background information, data
analysis, personal communication with technical experts, being informed of other studies
which were unpublished or in process and an examination of a sample of exhaust gas
suicide Victorian State Coroner’s case files.
Aim
To reduce the overall suicide rate in Australia by making motor vehicle exhaust gas suicide
substantially more difficult to undertake and complete.
Objectives of this study
• To review published and unpublished literature on the aetiology of suicide focussing on
access to the means, particularly motor vehicle exhaust gas suicides.
• To describe the epidemiology of motor vehicle exhaust gas suicides in Australia.
• To investigate :- the transference between means of suicide
- the relationship of exhaust gas suicide to vehicle numbers
- the Victorian Coroner’s files for the means and circumstances by which this
method of suicide is usually attempted
- possible solutions to exhaust gas suicide
- whether the legislated environmental limits on carbon monoxide (CO) emissions
have impacted on the numbers of suicide attempters selecting and succeeding by this
method.
- the international situation in regard to patterns, trends and possible solutions to
exhaust gas suicide.
• To make recommendations to relevant authorities and to disseminate the findings of this
study.
Suicide
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Social factors which are considered risk factors for suicide are those which relate to social
bonding: unemployment; never married, widowed or divorced marital status and nonchurch attendance. Age, sex, immigration and country of birth are also found to influence
suicide. Physical and mental health states are also known to be associated with the above
risk factors eg. terminal illness, depression, schizophrenia.
Methods of suicide
Physical availability and socio-cultural acceptability are considered necessary
preconditions for the choice of suicide methods. Methods chosen vary considerably in
lethality. Males have a propensity to use more immediate and violent methods than
females (eg firearms, hanging) and this partially accounts for their higher overall suicide
rates. Lethality rates have been reported at 85% for firearms, 80% for hanging, 77% for
exhaust poisoning, 75% for drowning and 23% for drug overdose.
In Australia, in 1995, four methods accounted for 84% of suicides - hanging, motor vehicle
exhaust gas, firearms and poisoning. There have been reductions over time in firearms and
poisoning. Exhaust gassings have constantly increased since at least 1968, despite the
introduction of catalytic converters in 1986. Hanging has seen the most dramatic rise. The
less frequent methods - jumping from high places, drowning and cutting and piercing vital
structures have varied little in the proportion of suicides they represent (approximately 3%
each). Poisoning is clearly the preference for females, although not to the previous extent.
Impulsiveness appears to play an important role, especially in youth suicide.
Cantor et al (1996) concluded that restricting the availability of a particular method of
suicide often, but not invariably, reduces overall suicide rates. A complex interaction of
factors will determine this outcome. If the method were made more difficult, then it could
take longer to affect, thus enhancing the possibility of the potential victim changing their
mind or being intercepted. Additionally, another method may not be acceptable.
Carbon monoxide
Carbon monoxide (CO) is colourless, odourless and tasteless and is produced from the
incomplete combustion of organic fuels. It attaches itself to the body’s red blood cells,
making the cells unable to carry oxygen. The brain and heart are the most susceptible to
toxicity because they depend most heavily on oxygen to function. Lasting effects on these
organs can include myocardial infarction, deterioration of personality and impaired
memory. Symptoms of carbon monoxide poisoning are normally a headache, drowsiness,
then loss of consciousness (LOC) and finally death. If the poisoning is not fatal hypoxic
brain injury can occur with possible symptoms of confusion, disorientation, incontinence,
amnesia, short-term memory loss and/or muteness.
Environmental CO requirements
The required maximum levels of CO in motor vehicle exhaust gases have been 24.3g/km
from July 1976 (ADR27A), 9.3 g/km from 1986 for new passenger vehicles (ADR37-00)
and 2.1 g/km for new models (ADR37-01) from 1997 and for all new passenger vehicles
from 1998. In order to cope with the unleaded petrol legally required since 1986, vehicles
usually require catalytic converters (ADR37-00, AS2877).
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
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Data analysis
•
The motor vehicle exhaust gas suicide (MVEGS) rates for Australia in 1995 were
calculated to be 4.69/100,000 males, 1.02/100,000 females and 2.85/100,000 total. In
1995, there were 509 cases of motor vehicle exhaust gas suicides in Australia. These
represented 21.5% of suicide cases.
•
The preference for this method of suicide varies between states. It appears to be a
relatively favoured method in Australia, particularly in the ACT and WA, compared
with other countries
•
MVEG has been more favoured in middle age and by males. In the 30-50 year age
group MVEG has been the leading means of suicide and 82% of all motor vehicle
exhaust gas suicides were male. Numbers were substantial in the 20-24 age group, this
being the age group which has had the highest suicide frequency overall.
•
Hospital admissions for Australian motor vehicle exhaust gas suicide attempts have
increased steadily in recent years (1994/95 data are not available), with the data
showing an exponential trend (R2=0.99). Deaths also increased, but show no clear
trend.
•
MVEG related self-harm represents a smaller proportion of hospitalised attempted
suicides (2%) than successful suicides (21.6%). This is likely to be the result of the
lethality of MVEG as a means of suicide compared to other means.
•
The age and sex distribution of MVEG related admissions is generally similar to that
seen for completed suicides. It appears however that younger males are relatively more
common among hospitalisations. This suggests that attempts among younger males are
more likely to be detected before death occurs presumably due to higher involvement
of their family.
Coroners’ records
•
Thirty-six percent of suicide vehicles had catalytic converters. This proportion was not
significantly different from the 39% of vehicles with catalytic converters in the
Victorian fleet.
•
In the 93 cases where the method was specified, all but 4 used a hose or pipe leading
into the interior of the vehicle with ventilation sealed.
•
The location of the vehicle in the 85 cases, where it was specified, was most frequently
at a home (51% cases), at an enclosed workplace (7%) or at an open-air location away
from home (including farm paddocks) (43%).
•
The median carboxyhaemoglobin level (COHb), for the 88 cases for which it was
noted, was 79%. The median COHb level of victims in the groups with and without
catalytic converters was identical (77.1%).
•
Alcohol was detected in 24 cases, benzodiazepines in 10, paracetamol in 8, cannabis in
7 and other pharmaceuticals, usually in a ‘cocktail’ in 7.
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MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
Several overseas studies which have examined the relationship between suicides and
MVEG have found that the imposition of emission controls reduces MVEGS. This
observation may in part relate to the comparatively newer vehicle fleet compared with
Australia (and to lower allowable emission levels.)
Explanations for suicides in later model vehicles
It appears that MVEGS have not reduced as much as expected with reductions in emission
levels and it is of note that the pattern between Australia, Japan and the USA may have
similarities ie a lagged levelling off after the introduction of CO exhaust limits.
Considerably less reductions are anticipated than would be expected if exhaust emission
CO levels of 2.1g/km made MVEGS impossible.
In explanation, it appears that there are several situations where the testing for these
legislated environmental CO limits may not be particularly relevant to the suicide lethality
situation eg 1) a hose or pipe is led into the interior of the vehicle and ventilation is sealed.
In this situation other gases eg. oxygen and CO2 and other factors such as heat and
humidity may have a synergistic and additive effect. It appears inappropriate that CO
limits are the same for each vehicle regardless of the vehicle’s cabin volume 2) the engine
idles. In environmental CO testing, there are 3 phases to the vehicle testing and none of
these involves idle only.
There are several situations where CO emissions may exceed the legislated limit such as 1)
where the engine idles from a cold start, with a delay of between 1.5 and 3 minutes before
the catalytic converter has warmed up and is operating efficiently. Since
carboxyhaemoglobin concentration rises most rapidly when first exposed to CO the initial
absorption rate would be particularly high 2) modern vehicles may be better sealed ie. less
ventilation and 3) the vehicle does not have a well-functioning catalytic converter.
Countermeasures
The cost per year attributable to 509 Australian motor vehicle exhaust poisoning deaths
was approximately $386.6 million in 1996, based on conservative figures. If a device were
developed which prevented 50% of these suicides and it cost $36, the full costs would be
recovered in just 2 years. Alternatively if a device cost $72, or if it prevented only 25% of
these suicides, the break even period would be 4 years. Furthermore there are additional
benefits of preventing several hundred hospital admissions resulting from failed MVEGS
attempts.
While it is considered that ultimately the solution should be in terms of performance
requirements for the vehicle there are several design solutions possible for the prevention
(or minimisation) of MVEGS:
Design Solutions
1. The mandatory incorporation into new vehicles of a multi-gas sensing device which
monitors carbon monoxide, oxygen and possibly carbon dioxide levels and when these
become life threatening displays a warning light, then emits an alarm and finally shuts
down the engine. The operation of window winding devices could also be incorporated.
Devices for the household which meet the Underwriters-Laboratory Inc. (UL) standard
2034 are available in the U.S for between AU$43 and AU$100 and a similar concept could
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
xiii
possibly be fitted to the engine management system of a motor vehicle. Currently these
alarms are activated at CO levels which produce COHb levels of 10% or above.
A CO detector attached to the engine management system of a motor vehicle would have
the added advantage of identifying and preventing unintentional poisonings and driver
fatigue due to leaks of carbon monoxide from unsealed boots, rusted holes and access
through open windows.
2. The exhaust pipe on new vehicles could be modified to incorporate a device inside the
pipe, so a hose cannot be inserted, and to make the end of the pipe irregular, to make it
difficult to fit a hose. New designs would need to overcome any problems of backpressure,
vibration or noise and would need to meet current exhaust regulations (eg exhaust gases
should be emitted beyond the vehicle).
Both approaches showed sufficient promise of a potential cost-effective contribution to the
prevention of MVEG and warrant further expenditure on research. Research would better
define what is involved and provide more precise estimated values for the assumptions
made above.
3. Further improvements could be made to engine design and in catalytic conversion
techniques to complete the combustion process and thereby virtually eliminate carbon
monoxide emissions.
It is recognised that design changes will not eliminate all suicides. Complex social,
economic and psychological reasons underlie the causes of suicide and the solutions for
these require a multi-faceted longer term approach.
Recommendations
1.
Mandatory regulations should be introduced for new vehicles which will make
exhaust gas suicide virtually impossible, by ensuring that life threatening levels of
CO, O2 and possibly CO2 cannot be reached by passing a hose from the exhaust into
the vehicle with sealed ventilation. A sensor is preferred because it would cater for
deterioration in catalytic converter and engine performance over time.
2.
Regulations should be introduced for in-service vehicles requiring replacement
exhaust pipes to be of new safety designs to make it substantially more difficult to
attach a hose.
3.
A study of MVEGS attempters (ie those admitted to hospital) should collect
information which further clarifies potential countermeasures and risk factors.
Variables on which it would be important to collect data are: how long the vehicle
ran, if they were interrupted, if they reneged, the reason for selection of the MVEG
method, the practical details of how they made the attempt eg. equipment used, the
blood alcohol content and if possible the presence of other drugs, if they had
previously attempted suicide by exhaust gas or otherwise and information on the
make, model and year of manufacture of the vehicle. Such data would be most
useful in gaining further insight into how MVEGS are undertaken and the extent to
which catalytic converters are making an impact. Data collected so far has
concentrated on deaths.
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MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
4.
The Suicide Module of the National Coronial Information System should collect
information encoded and/or in text including the make, model and year of
manufacture of the vehicle; COHb level; drugs, medications and other gases
detected at pathology; practical details of the attempt including equipment used;
details of previous attempts. Additionally there should a move towards consistency
in the medical and legal definitions of suicide.
These actions should be undertaken quietly, without media attention. Adding to the risk
group’s knowledge of how to undertake this method, or risking ‘copycat’ suicides, should
be avoided.
Progress
The Mental Health Branch of the Department of Health & Family Services was given
responsibility for the allocation of $30,000 to alleviate exhaust gassing suicides.
Since November 1996 there have been four meetings convened by the Australian Medical
Association and initially the Federal Office of Road Safety to reduce vehicle exhaust gas
suicides with representatives from various interest groups.
The priority recommendations for the allocation of the H&FS $30,000 have been revised.
These are now:
•
$6,000 to bring Prof David Penney, Director of Surgical Research and Professor of
Physiology, Wayne State University, US, an expert on the physiological effects of CO
to the April 1998 meeting in Melbourne to determine an appropriate CO level for a CO
detector. He will produce a report in September, 1998.
•
$15,000 to research MVEGS attempters who have been treated for CO poisoning at the
Prince of Wales Hyperbaric unit. The study is in progress and the reasons for their
method choice, demographic profile, details of psychiatric records and any previous
suicide attempts by MVEGS or other methods and the details of their latest MVEGS
attempt, including the presence or otherwise of catalytic converters are being studied.
•
$5,000 to an industrial design student at Flinders University to research the available
exhaust pipe designs and to design a tailpipe which is low cost (including fitting),
which does not cause problems of backpressure or reduce performance etc and which
allows a vacuum or garden hose or other pipe to be fitted only with great difficulty. A
design has been produced which meets these criteria.
•
$4,000 to develop a computer model which simulates the exhaust gassing suicide
scenario. Mr Jerry Moller has now submitted a paper which includes a model of CO
and O2 exhaust gas concentrations to the Department of Health and Family Services
Mental Health Branch.
In addition, the Australian Automobile Association has allocated $15,000 to RMIT in
Melbourne for the development of a CO sensor for the vehicle cabin. Currently the
emphasis is on developing CO, O2 and CO2 detectors. The focus will then be to link these
into a multi-sensor system. Additional funds are likely to be required for development to
the next stage.
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
xv
International enquires have identified very little activity to reduce suicides by this method
and it appears that this committee is leading the way internationally.
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MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
Glossary
AAA
Australian Automobile Association
AAAA
Australian Automotive Aftermarket Association
ABS
Australian Bureau of Statistics
ADR
Australian Design Rule
AMA
Australian Medical Association
AISRAP
Australian Institute of Suicide Research and Prevention
AS
Australian Standard
CO
carbon monoxide
CO2
carbon dioxide
COHb
carboxyhaemoglobin blood level
EPA
Environment Protection Authority
FORS
Federal Office of Road Safety
g/km
grams per kilometre
ICD
International Classification of Diseases
MUARC
Monash University Accident Research Centre
MVEG
motor vehicle exhaust gas
MVEGS
motor vehicle exhaust gas suicide
NOHSC
National Occupational Health and Safety Commission
O2
oxygen
ppm
parts per million
RMIT
Royal Melbourne Institute of Technology, Melbourne
STEL
short-term exposure limit
TWA
time weighted average
RACV
Royal Automobile Club of Victoria
US
United States
VISS
Victorian Injury Surveillance System
WHO
World Health Organisation
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xviii MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
1.
INTRODUCTION
1.1
RATIONALE
1.1.1
Australian Data
Suicide is a major problem in Australia. In recent years there have been approximately
2000 deaths each year from suicide. Since 1990 suicide has been more common than motor
vehicles crashes as a cause of death. In 1996 motor vehicle exhaust gas was the second
major method of suicide, accounting for almost 22% of suicides. It was the method most
commonly used by middle-aged males.
1.1.2
Potential for Prevention
There is evidence that reduction in access to a lethal means potentially reduces the overall
suicide rate. Cantor et al (1996) concluded in their report on youth suicide that restricting
the availability of a particular method of suicide often, but not invariably, reduces overall
suicide rates. There is potential for reduction where the method takes longer to affect thus
increasing the possibility of interception or a change of mind, where the method may fail,
where no culturally acceptable or accessible method is available for substitution or where
the substituted method is less lethal. The potential for reduction is greatest where the
restricted method is commonly used. Motor vehicle exhaust gassing fits many of these
criteria.
1.2
BACKGROUND
The Victorian Injury Surveillance System (VISS), a project of Monash University
Accident Research Centre (MUARC), is funded by the Victorian Health Promotion
Foundation. VISS identified motor vehicle exhaust gassing suicides (MVEGS), as a major
means of death in Victoria, in its quarterly publications Hazard 11 ‘Victorian Injury
Deaths and the Potential for Prevention’ (June 1992) and Hazard 20, ‘Non-traffic motor
vehicle related injuries’ (September 1994). Its importance was further validated in the
MUARC report ‘Injuries in the Middle Years’. MUARC staff wrote to motor vehicle
manufacturers, automotive bodies, government departments, suicide prevention
committees and the Australian Medical Association (AMA) outlining the problem and
making recommendations for prevention. Papers on this topic were presented by MUARC
staff at national and international injury and suicide prevention conferences and an article
was published in the Medical Journal of Australia (19 January 1998).
The AMA has a history of periodically pursuing this issue, and in recent years undertook
this through its Ethics, Science and Social Issues Committee. Influenced by MUARC, at
the end of 1996 the AMA and the Federal Office of Road Safety (FORS) convened a
meeting to examine the issue with interested parties. MUARC staff attended this meeting
and have been involved in on-going activities. MUARC staff members were consulted for
the Commonwealth Department of Health and Family Services Youth Suicide Prevention
Advisory Group’s background report ‘Access to means of suicide by young Australians’
by the Australian Institute for Suicide Research and Prevention. MUARC was represented
on the ‘Access to Means’ Working Group of this Advisory Group. In 1997, MUARC
prepared a submission to and was consulted by the Victorian Youth Suicide Taskforce.
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
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Since mid-1994, MUARC has continued to research and be involved in activities to reduce
exhaust gassing suicides. In addition, MUARC has assisted the Coroner to design a
relational database, as a source of detailed death data for Victoria. All of these activities
have been made possible by funding from the Victorian Health Promotion Foundation in
supporting applied research and the translation of research into injury prevention.
1.3
THE STUDY
1.3.1
Overview
The study involved a literature review and obtaining background information on suicide
and suicide method, particularly exhaust gas suicide, data analysis, personal
communication with technical experts, being informed of other studies which were
unpublished or in process, an examination of a sample of exhaust gas suicide Victorian
State Coroner’s case files and checking registration records for age of vehicles.
1.3.2
Literature review
A literature search was undertaken of the Medline, Suicide Information & Education
Centre (Canada) and SESAME (Monash University) library systems. Relevant references
listed in the bibliographies of reviewed references were located.
The literature was initially reviewed and information sought to provide an overview of
suicide, its patterns in Australia and factors which influence suicide rates. Methods of
suicide were then reviewed, particularly determinants of choice, methods used and
differences of classification. The restriction of means and the transference between means
of suicide was also investigated. Finally there was a brief reference to parasuicide ie
suicide attempts.
The second stage involved obtaining information on carbon monoxide poisoning and
finally motor vehicle exhaust gas suicide.
1.3.3
Aim
To reduce the overall suicide rate in Australia by making motor vehicle exhaust gas suicide
substantially more difficult to undertake and complete.
1.3.4
Objectives
• To review published and unpublished literature on the aetiology of suicide focussing on
access to the means, particularly motor vehicle exhaust gas suicides.
• To describe the epidemiology of motor vehicle exhaust gas suicides in Australia.
• To investigate :- the transference between means of suicide
- the relationship of exhaust gas suicide to vehicle numbers
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- the Victorian Coroner’s files for the means and circumstances by which this
method
of suicide is usually conducted
- possible solutions to alleviate the problem of exhaust gas suicide
- whether the legislated environmental limits on carbon monoxide (CO) emissions
have impacted on the numbers of suicide attempters selecting and succeeding by
this method.
- the international situation in regard to patterns, trends and possible solutions to
exhaust gas suicide.
• To make recommendations to relevant authorities and to disseminate the findings of this
study.
1.3.5
Method
Data
Analysis was undertaken of Australian hospital admissions data for motor vehicle exhaust
gassing suicide attempt trends. The most important source however was the Australian
Bureau of Statistics (ABS) Australia wide death data for exhaust gas suicide and total
suicides by age, sex and state of residence. US suicide data was also obtained and
analysed. Comparisons were made with Dutch, Japanese, Norwegian and New Zealand
data.
“Gases and other vapours” suicide rates (almost all exhaust gassings) were obtained from
the Australian Institute for Suicide Research and Prevention and recent Australia wide
hospital admission MVEGS frequencies and rates from the National Injury Surveillance
Unit, Research Centre for Injury Studies, Flinders University.
Vehicle numbers, rates per head of population and the distribution by model, make and
year of manufacture were obtained from ABS publications.
Exhaust gas suicide case lists collated from the findings of the Victorian State Coroner
listed in the publication of the Victorian State Coroner’s Office ‘Unnatural Deaths
1993/94’ were analysed for reasons for suicide.
Victorian State Coroner’s Files
These were examined to:
a) Determine if the vehicle used was manufactured post-1986 ie had a catalytic converter
fitted (as required by Australian Design Rule 37-00 and Australian Standard 2877).
b) Locate additional information relating to where the suicides were undertaken; the
practical details of how they were carried out; the type of hoses, pipes if any, used; the
blood level of carbon monoxide (CO) (carboxyhaemoglobin level (COHb)); any other
drugs taken; if notes were left; any leads as to why they sought to end their life and the
age and sex of the victim. It was expected that not every file selected would provide all
variables.
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Case numbers of a sample of thirty-three 1994 motor vehicle exhaust gas suicides were
obtained from case listings in ‘Unnatural deaths’ 1993/94, State Coroner’s Office,
Victoria, the latest publication providing these details. The details in (b) were obtained
where possible. Vehicle registration numbers were then checked for the make, model and
year of manufacture.
Case numbers of 1995 and 1996 deaths were then provided from the Coroner’s Facilitation
System database and data on variables listed in (b) were collected from a sample of 1995
and 1996 cases where available. The year of manufacture, make and model were obtained
where registration numbers were provided.
Personal communication
Discussions, mostly by telephone were held with experts in their particular field. These
provided background and technical information. They occurred with staff from
Environment Australia, the Hyperbaric Unit (Alfred Hospital), Royal Automobile Club of
Victoria (RACV), some motor vehicle manufacturers, injury researchers in Australia and
internationally, automotive mechanics, engineers and road safety researchers.
Other
Information on relevant news articles, researchers undertaking relevant studies etc were
followed up.
1.3.6
Results
The majority of the results are in the Results section, chapter 4 but it was considered more
appropriate to include others in sections where they were highly relevant eg U.S. data with
relevant information from journal articles.
The results of the analysis of the ABS suicide method data are presented as part of suicide
background information in Chapter 2 and the data on the relationship between MVEGS
and motor vehicle registrations in Australia as part of motor vehicle exhaust gas (MVEG)
background information in Chapter 3. The ABS exhaust gas suicide data, hospital
admissions for exhaust gas suicide attempts, reasons for suicide taken from the Coroner’s
Facilitation System MVEGS narratives, analysis of data extraction from the Victorian
MVEGS Coroner’s files are all included in chapter 4. Also in chapter 4, under
‘Discussion’, are details of other studies and additional information required. The results of
the U.S data analysis are included in chapter 5, ‘The impact on MVEGS of emission
controls’ under U.S data.
1.3.7
Recommendations, Conclusions and Progress
These, with the costs and benefits of prevention are briefly outlined in chapter 6.
Suggestions are made for design solutions and recommendations made for action. Progress
to date is described.
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2.
LITERATURE REVIEW AND BACKGROUND INFORMATION SUICIDE
2.1
SUICIDE OVERVIEW
2.1.1
Introduction
Suicide is generally accepted to mean the fatal, and suicidal attempt, the non-fatal act of
self-injury, undertaken with more or less conscious self-destructive intent, however vague
and ambiguous. Suicide is ubiquitous. There is no period in history without records of
suicides, the belief that it does not occur in primitive societies has proved to be mistaken
(Stengel, 1969).
However there is a range of definitions according to purpose. The Coroner’s definition
based on legal rules is the most strict. The Coroners must determine that the person had the
intention to commit the act, that they had the intention to commit death by the act and that
at the time of committing the act they were capable of understanding it would result in
death. The Australian Bureau of Statistics and hospital admissions use the ICD E code
definition which is more aligned with self-inflicted injury leading to death and is consistent
with world health practice. Some deaths will therefore be included where the Coroner did
not make a formal finding of suicide (Moller,1997).
Some deaths, in Australian mortality data, are classified as being of undetermined intent
(2.5% of injury deaths in 1992). Many of these were probably suicides, though some may
have resulted from accidental causes or homicide (Harrison et al, 1994). Undetermined
intent may also be an important factor in differentials between reported rates between
countries.
In recent years there have been approximately 2000 deaths in Australia each year from
suicide and there were 13,721 hospitalisations from intentionally self-inflicted injury in
1992/93. Since 1990, suicide has been more common than motor vehicles as a cause of
death in Australia (Moller, 1996).
2.1.2
Suicide Patterns in Australia
The trend in suicide since 1922 is shown in Figure 1. Over the last 20 years, the pattern of
suicide in the community has changed, with suicide becoming less common among
middle-aged men and women but more common among the young. Much of this increase
is due to the growing number of suicide deaths among younger males (figure 2). Similarly
to Australia, five industrialised countries, New Zealand, Norway, Switzerland, Canada and
the USA, have high youth suicide rates (Commonwealth Department of Human Services
and Health, 1995). There is also increasing prominence of males in rates of attempted
suicide. Previously rates of attempted suicide, especially at young ages, were much higher
for females than males (Harrison, 1994). Australia’s suicide rate is similar to that
experienced in many other countries, including the United States and Canada
(10.4/100,000). It is higher than the rates recorded in the UK and Italy, but lower than the
rates reported in Hungary and Finland (Australian Bureau of Statistics, 1994).
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
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Figure 1. Suicide-standardized mortality rates Australia 1922-92
(Source: Harrison et al. Australian Injury Prevention Bulletin NISU Issue 5, February 1994.)
Figure 2. Male suicide rates Australia 1922-92 by age group
(Source: Harrison et al. Australian Injury Prevention Bulletin NISU Issue 5, February 1994.)
The age standardised suicide rates in Australia in 1993 were 19.3/100,000 for males, and
4.4/100,000 for females and 11.7/100,00 total. Female rates of hospital admission due to
suicide attempts are higher than male rates. This suggests a propensity for males to choose
more lethal means (Harrison et al, 1994).
2.1.3
Factors influencing suicide rates
Durkheim in Le Suicide in 1897 was the first to report on suicide from the sociological
rather than the psychological perspective. He considered social bonds to relate individuals
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to the society through integration or norms. If the social bonds are either too weak or too
strong their integrative and regulative functions are rendered ineffective, in which case
people are vulnerable to suicidigenic currents of 4 different kinds - egoism, altruism,
anomism and fatalism (Cheek et al, 1996).
If the social bonds of attachment are weak the individuals are free from dependency on the
group, its values and expectations, and with few social ties, an excessive individualism
prevails such that more people are predisposed to egoistic suicide. Religion, marital status
and political stability were included by Durkheim under this suicidigenic current. Anomic
suicide can occur in societies undergoing such rapid and profound social change that
traditional norms are dislocated and a sense of uncertainty prevails. People feel at a loss to
know how to orient themselves towards society, how to behave and how to be in the world.
He considered there to be 2 types of anomic suicide - economic and conjugal. (Cheek,
1996).
Durkheim observed that one of the strongest protections against suicide was to belong to
an organised work force. Unemployment or work loss weakens the individual’s social
integration, deprives him or her of a social role and status and increases social isolation, all
of which are positively correlated with higher risk (Hassan, 1995).
Similarly Kellehear more recently noted that ‘unemployed people often experience social
disapproval, dependency, abandonment and loss of social worth. Modern industrial
economies place work at the centre of social experience and define self-worth accordingly.
It is the overriding identification and status system of the day’ (Kellehear, 1990).
Windshuttle studied relationships between Australian unemployment rates and suicide
rates since 1900 and found, although female suicide rates fluctuated relatively little during
the period, male rates showed peaks and troughs corresponding to the unemployment rate.
The period of increasing youth suicide strongly corresponds to the current high youth
unemployment rate (Windshuttle in Hassan, 1995).
Recent data from the Australian Bureau of Statistics strongly confirm the relationship
between the various marital statuses and suicide. Between 1986 and 1990, married men
and women had significantly lower suicide rates. Never married, divorced and widowed
men had a suicide rate about twice that of the general population, and three times that of
married men. The marital status pattern of suicide among women is similar to that of men
(Hassan, 1995).
Church attendance rather than allegiance has been the variable of those associated with
religion that is most closely tied to the variation in suicide attitudes. Pescosolido and
Georgianna (1989) argued that denominations that are in tension with societal culture,
conservative, and nonecumenical and whose power structures are non-hierarchal should
have lower suicide rates eg Seventh Day Adventists. These kinds of church structures
facilitate friendship ties among members of their congregation and these ties act as
important sources of social support which reduce suicide risk (Maris, 1992).
Other demographic and socio/cultural factors found to influence suicide are age, sex,
immigration and country of birth.
Immigration to a new country or community invariably involves disruption of established
social ties, thus adversely affecting the degree of social and community integration for the
immigrant (Hassan, 1995). Ruzika and Choi found suicide rates to be higher for
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
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immigrants than non-immigrant counterparts in their country of birth. Males in Australia
who were born in New Zealand, Germany or Yugoslavia had significantly elevated suicide
rates, while rates for men born in Italy or Greece were significantly lower than expected
(case numbers were too small to allow analysis for many countries of birth) (Harrison,
1994).
Durkheim, writing in the late 19th century, considered social bonds to be stronger, and
suicide rates therefore lower, in rural areas. Although the latter has been the situation in the
past in Australia, rural suicide rates have been lower in the past decade for females only
(4/100,000 rural v 5/100,000 urban, 1992). Males in rural areas, especially those in the 1524 year age group, had higher suicide rates than those in urban areas (26/100,000 v
20/100,000, 1992) (Australian Bureau of Statistics, 1994). The relatively high rate for rural
males can partly be attributed to the more frequent use of firearms, a highly lethal method.
The firearm suicide rates for males were 3.5/100,000 for capital cities, 7.9/100,000 for
rural major, 11.6/100,000 for rural other and 18.6/100,000 for remote other over the
period 1990-92 (Moller, 1994). It appears that the more remote an area the higher the
firearm suicide rate.
Moller in his analysis considered males aged 15 to 19 years and 40 to 59 years to show a
pattern of elevated risk in rural and remote areas. A finer level of examination shows that
the high suicide rates coincided with rural production areas (ie rural other) rather than
rural towns, for the younger males. The higher rates of the male middle-aged group
coincided with the age distribution of the agricultural and forestry industry male worker
populations. He considered that these rates may reflect the impact of the rural recession
(Moller, 1994). The social bonds of the past therefore may have been counteracted by the
tougher economic climate.
Gibbs and Martin formed 5 postulates linking the suicide rate of a population with:
• the stability and durability of social relationships within a population
• the degree of status integration in that community
• the extent to which individuals in that population
- conform to the patterned and socially sanctioned demands and expectations placed
on them by others
- are confronted with role conflicts
- occupy incompatible status
(Hassan, 1995).
The issue of exposure of adolescents to information about suicides either through personal
knowledge of cases or via the mass media (“copy cat” suicides) is an issue on which
studies conflict and it cannot be regarded as resolved. The peak in numbers of deaths by
hanging in police custody seen in several Australian states in 1987 might be an instance of
this phenomenon (Harrison, 1994). A recent phenomenon is interactive suicide notes on
the internet and these have been investigated by Baume et al, 1997.
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In addition to these sociological factors there is the risk state of the individual. Some
mental health professionals stress the influence of underlying pathology among completed
suicides eg depression (Harrison at al, 1994).
2.2
METHODS OF SUICIDE
2.2.1
Determinants of choice
Little is known about the determinants of the choice of method. Researchers have
suggested physical availability and socio-cultural acceptability are necessary preconditions
for the choice of suicide methods (Clarke & Lester, 1989; Hassan, 1995). Socio-cultural
acceptability is a measure of the extent to which a person's choice of method is shaped and
circumscribed by the norms, traditions and moral attitudes of their culture. The existence
of one without the other is unlikely to result in the potential method being selected eg fire
is widely used for suicide in certain Asian cultures (Sheth, Dziewulski and Settle, 1994)
but is rare in Australia despite the ready availability of matches and petrol. To date, most
research into suicide methods has focussed on availability and method choice, without
simultaneously considering socio-cultural acceptability (Cantor et al, 1996).
Clarke and Lester (1989) synthesised the results of numerous studies and determined a list
of 'choice structuring properties' or key factors presumed to influence method choice.
These were familiarity with the method, technical skills, planning, courage needed (high
buildings, train), likely pain, disfigurement after death, danger/inconvenience to others (car
crash, subway leap), messiness, gender association, scope for second thoughts, chances of
intervention, certainty of death, contamination of the “nest”, discovery of the body (loved
ones or strangers), scope for concealing or publicising death (shame, insurance - car-crash,
drowning), time taken to die while conscious (poisons, wrist cutting), symbolism
(cleansing by fire) and dramatic impact (Clarke & Lester, 1989 in Cantor et al, 1996).
Methods chosen vary considerably in 'lethality' - the probability of death. Males have a
propensity to use more immediate and violent methods than females (eg firearms, hanging)
and this partially accounts for their higher overall suicide rates. Kleck (1992) reported a
gun lethality rate of 85%, 80% for hanging, 77% for exhaust poisoning and 75% for
drowning. Card, in 1974, had found similar figures, although he gave a figure of 23% to
drug overdose, a figure which should by now have dropped considerably due to reduced
availability and improved treatment methods. Lethality is partly dependent on the length of
time that elapses between the suicide event and death (McIntosh, 1992) eg poisoning v
hanging. Literature suggests that a much larger number of people survive actual suicide
attempts than die by them (Cantor et al, 1996).
2.2.2
Methods used
Epidemiological studies have shown that the popularity of particular methods of suicide
changes within and between countries over time (eg Pounder 1991; Curran and Lester,
1990).
Despite the potentially large number of methods of suicide, only relatively few methods
are widely used. These methods, in western countries, typically include poisoning by
prescribed and non-prescribed drugs, poisoning by domestic gas and motor vehicle exhaust
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
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gas, hanging, firearms, cutting and piercing, drowning, jumping from high places and lying
or jumping in front of vehicles (Cantor et al, 1996).
In Australia, in 1995, four methods accounted for 84% of suicides - hanging, motor vehicle
exhaust gas, firearms and poisoning by solid or liquid substances. The trends in these
methods over time, excluding vehicle exhaust gassings, are shown in Figures 3 and 4 and,
more recently, including all major methods in figure 5. The high poisoning rates in the
1960’s could be attributed to the easy availability of barbiturates and the subsequent
decline due to restrictions on their availability. Unfortunately not shown on these graphs is
the elimination of coal gas as a method in the late 1960’s, early 1970’s.
Figure 3. Method of suicide-age standardized mortality rates Australia
1922-92, males
(Source: Australian Injury Prevention Bulletin NISU Issue 5, February 1994)
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Figure 4. Method of suicide-age standardized mortality rates Australia
1922-92, females
(Source: Australian Injury Prevention Bulletin NISU Issue 5, February 1994)
The past 25 years has seen a continuing reduction in the percentage of suicides represented
by poisoning, due to stricter scheduling restrictions and better treatment methods. Since
1980, there has also been a reduction in firearm suicides. The latter would have been
impacted on by the increased firearm restrictions in 1988 in Victoria. These were followed
by a reduction in total firearm suicides of 32% for the 6 years post-legislation compared
with the 6 years prior to legislation (based on ABS data).
Exhaust gassings have constantly increased since at least 1968, despite the introduction of
catalytic converters in 1986. Hanging has seen the most dramatic rise (figure 5). The less
frequent methods - jumping from high places, drowning and cutting and piercing vital
structures have varied little in the proportion of suicides they represent (approximately 3%
each).
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Figure 5. Means of suicide as a % of total Australian suicides
%
40.0
35.0
30.0
Poisoning
Exhaust gas
Hanging
Firearms
25.0
20.0
15.0
10.0
5.0
0.0
1970
1975
1980
1985
1990
1995
Year
(Source: Based on Australian Bureau of Statistics data.)
Suicide method preferences by sex are shown in Table 1. Poisoning is clearly the
preference for females, although not to the extent previously. In 1970, 59% of female
suicides were poisonings, compared with only 8% hangings and 3% vehicle exhaust (9%
were domestic coal gas). For males in 1970, firearms accounted for 35%, poisoning 28%,
but hanging and motor vehicle exhaust gas were only 12% and 10% respectively.
Table 1. Methods of completed suicide - Australia
Method
Hanging
Motor vehicle exhaust
Firearms
Poisoning
Jumping from high places
Drowning
Cutting & piercing
Other & unspecified
Total
Males (n= 1931)
%
34.8
22.4
19.1
10.3
4.1
1.6
1.5
6.2
100
(Source: Based on Australian Bureau of Statistics data, 1996)
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Females (n=462)
%
26.0
15.2
3.2
38.7
4.3
3.5
1.7
7.4
100
2.2.3
Restriction of method
The rationale to restriction on access to the means of suicide is based on several elements.
Firstly, impulsiveness appears to play an important role, especially in youth suicide. For
practically all suicides, ambivalence is a prominent characteristic ie the determination to
commit suicide waxes and wanes. For these reasons, many suicide prevention specialists
argue that, if lethal means are not readily available when a person decides to attempt
suicide he or she might either (1) delay the attempt, allowing for the possibility of later
deciding against suicide or (2) use a less lethal means, allowing for a greater possibility of
medical rescue. Means restriction, therefore, has the potential for preventing suicides, even
if it does not decrease the incidence of suicide attempts. At least some portion of impulsive
decisions to attempt suicide might never be acted upon if substantial efforts were needed to
arrange for a method of suicide (National Center for Injury Prevention & Control, 1992).
Additionally if the method were made more difficult, then it could take longer to affect,
thus enhancing the possibility of the potential victim changing their mind or being
intercepted.
A recent report on access to means reviewed the international and Australian literature on
the relationship between 'access to means' and suicide rates and found:
(i)
Increased availability of a culturally accepted method of suicide tends to result in
an increase in the suicide rate for that method.
(ii)
Restricting the availability of a particular method of suicide tends to result in a
corresponding decline in suicide rates for that method (Cantor et al, 1996) e.g. the
tightened gun laws in Victoria since 1988 have coincided with a reduction in
suicide by firearms (ABS, 1996).
2.2.4
Transference between methods of suicide
Environmental influences appear to have a role in creating and combating suicide
epidemics. The phasing out of coal gas and the introduction of petroleum gas in Australia
was accompanied by a fall in such suicides in Australia. This intervention has been well
documented in Britain as reducing the overall suicide rate (Harrison and Moller, 1997). In
Britain, in 1975, the overall suicide rate was 75% lower than in 1960. In the UK circa 1960
coal gas suicides peaked at 2,600 pa - overall suicides circa 5,100. With subsequent
domestic gas detoxification, coal gas suicides fell to almost zero by 1972. This was not
associated with an inverse corresponding change in any other method of suicide.
Moreover, overall suicides correlated with coal gas trends (Cantor et al, 1996). The
widespread availability of relatively hazardous barbiturates in Australia coincided with
high rates of suicide in the 1960's, especially for females. The restriction of these drugs
coincided with a marked fall in overall suicide rates (Harrison et. al., 1996) (figure 4).
These findings are consistent with different methods of suicide exerting independent
influences.
Lester and Frank (1989) found that states in the USA with higher per capita ownership of
cars had higher suicide rates by MVEG. Lester replicated this investigation for 28 nations
and found that nations with more cars per capita had higher rates from other gases and
vapours (the E-code category E952 which consists almost entirely of carbon monoxide
suicides). However they did not have equivalent reduced rates from other means,
indicating that switching to other methods for suicide did not take place (Lester, 1994).
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As domestic gas was made less toxic in Northern Ireland during the period 1960-88, it was
used less often for suicide. However, during the same period, as car ownership increased,
the use of car exhaust for suicide increased in popularity, without there being a
corresponding decrease in the use of other methods (Curran, Lester, 1990). Burvill
likewise suggested that, in Australia, substitution of domestic gas with exhaust gas
occurred with no significant reduction in the overall suicide rate (Burvill, 1980).
Another example where means restriction was not successful in reducing the overall rate of
suicide was in Surinam where a government ban on the sale of undiluted acetic acid (a
common means of suicide in that country) prevented virtually all suicides by that method.
The decline in such suicides was almost completely offset by a concomitant increase in
suicides by ingestion of paraquat, a potent herbicide widely available in Surinam. Suicides
by ingestion of agricultural poisons were already on the rise in Surinam (National Center
for Injury Prevention & Control, 1992).
Clearly, restriction of a means of suicide is more likely to affect the overall suicide rate if
that suicide method is common. Marakush and Bartolucci (1984) and Lester (1984) have
shown that the availability of firearms is related to their use for suicide and to the overall
suicide rate in the U.S. (Lester, 1989). Lester found that the greater availability of guns in a
country, the lower the suicide rate by other methods, and that people appeared to switch to
this method as firearms became increasingly available (Lester, 1990,1994).
Cantor et al concluded that restricting the availability of a particular method of suicide
often, but not invariably, reduces overall suicide rates. A complex interaction of factors
will determine this outcome. There has been a tendency to neglect the influences of
independently evolving methods of suicide.
It may be erroneous to suggest that societies respond uniformly and collectively to changes
in the availability of different methods of suicide. Restrictions on methods of suicide will
have different impacts according to complex psychological, social and environmental
phenomena at the time. The relevant question is: to what extent, and under what
circumstances, does substitution occur? (Cantor et al, 1996)
2.3
ATTEMPTED SUICIDES
According to Maris, depending on their age and sex, nonfatal suicide attempters (not
necessarily hospitalised) outnumber suicides by at least 8 or 10 to 1 (Maris, 1992). Other
estimates have been considerably greater. As indicated by hospital admission rates, selfinflicted injury victims are more likely to be female and drug overdose cases. The average
annual rates for Victoria between July 1987 and June 1993 were 54/100,000 for male selfinflicted injury, 43/100,000 for male self-inflicted poisonings; 78/100,000 for female selfinflicted injury and 72/100,000 for female self-inflicted poisonings (Watt, 1995).
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MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
3.
LITERATURE REVIEW AND BACKGROUND INFORMATION CARBON MONOXIDE
3.1
CHARACTERISTICS OF CARBON MONOXIDE POISONING
Carbon monoxide (CO) is colourless, odourless and tasteless and is produced from the
incomplete combustion of organic fuels. CO has been a problem for humans ever since our
ancestors learned to build fires in unventilated shelters. Although the primitive fuels of
preindustrial societies produced large amounts of CO, they also emitted irritating gases
that warned of a dangerous exposure. Today’s clean fuels provide us with a much greater
opportunity for exposure to CO (Cobb, Etzel, 1991). It is present in smoke from fires,
cigarettes and charcoal burners and from motor vehicle exhausts.
Poisonings are caused by CO binding to the 5 points of the haemoglobin molecule faster
than oxygen, thus not allowing oxygen to penetrate. Normal concentrations of carboxyhaemoglobin (COHb) in non-smokers living in an urban environment are less than 2% and
in smokers concentrations may reach 5%. Levels that exceed 50% saturation are
considered life threatening (Victorian Coroner’s autopsy notes, 1996), although the
victim’s age and pre-existing morbidity may affect this (New et al, 1996).
The presence of CO is not detectable by humans. CO attaches itself to the body’s red blood
cells, making the cells unable to carry oxygen. As blood travels through the body, CO is
passed to the organs rather than oxygen. All systems of the body can be affected by CO
poisoning. However, the brain and heart are the most susceptible to toxicity because they
depend most heavily on oxygen to function. Lasting effects on these organs can include
myocardial infarction, deterioration of personality and impaired memory (Willis Hurst et
al, 1990; Smith, Brandon, 1973).
The carboxyhaemoglobin concentration in the blood rises rapidly at the beginning of the
CO exposure and then progressively more slowly to an equilibrium. The time taken to
reach equilibrium depends on the concentration of CO in the inspired gas and the level of
pulmonary ventilation (figure 6) (Ernsting and King, 1988). CO uptake is also influenced
by the levels of carbon dioxide (CO2) and oxygen (O2) and to a more minor extent by heat,
humidity and up to ten other factors (Penney,D, 1998). Figure 6 shows COHb levels for
very low levels of CO, for example at a CO concentration of 0.05%, the 50% COHb
concentration may never be reached. There is not complete agreement on these measures
and the influences of other gases and factors have not been taken into account in the
plotting of this graph.
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
15
Figure 6. The time courses of the concentrations of carboxyhaemoglobin in
the mixed venous blood on exposure to breathing CO at inspired
concentrations of 0.01%, 0.05% and 0.1% in air, at rest (broken lines) and
during light exercise (solid lines).
(Source: Ernsting & King, Aviation Medicine, 2nd ed. Butterworths, 1988.)
Symptoms of carbon monoxide poisoning are normally a headache, drowsiness, then loss
of consciousness (LOC) and finally death. The tissues most sensitive to hypoxia, such as
those of the nervous system, are the first to be affected (Ernsting & King, 1988). Young fit
males absorb CO at a relatively high rate and therefore record higher levels of CO at death.
If the poisoning is not fatal hypoxic brain injury can occur with possible symptoms of
confusion, disorientation, incontinence, amnesia, short-term memory loss and/or muteness.
Independent living is not always possible after the event and the survivor and their family
will require counselling. Brain injury may not always be immediately apparent and
symptoms may not manifest themselves until several weeks later (New et al, 1996).
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MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
Table 2 Symptoms induced by various blood concentrations of CO (at sea level with
normal haemoglobin level)
Saturation of
haemoglobin with CO
% COHb
Less than 10
10
20
30
40-50
60-70
Symptoms
None
No appreciable effects other than mild headache and slight
dyspnoea on vigorous exertion
Slight headache, fatigue and dyspnoea even on mild exertion
Headache, increasing fatigue, impaired judgement and gross
dyspnoea and impairment of vision on exercise
Severe throbbing headache, confusion, fainting and collapse
even at rest
Unconsciousness
(Source: Ernsting & King, Aviation Medicine, 2nd ed. Butterworths, 1988.)
Table 2 refers to the symptoms associated with various COHb levels. The Victorian
Coroner’s autopsy notes refer to a mean of 72% and levels above 50% being life
threatening.
3.2
CO STANDARDS
In May 1995 the Australian National Occupational Health and Safety Commission
(NOHSC) released a new exposure standard for CO, a reduction from levels published in
1991. The time weighted average (TWA) exposure standard, is now 30 parts per million
(ppm) measured over an 8 hour work day, 5 day work week. NOHSC also state ‘to
maintain compliance with 5% COHb, a short term exposure limit (STEL) of 100ppm
would have to be applied’. The STEL is measured at four 15 minute intervals, each
separated by one hour, provided the TWA is complied with. The NOHSC exposure
standard is set to ensure that CO exposure from work results in a blood COHb below 5%, a
level which provides protection against the adverse effects of CO (Victorian Workcover
Authority, 1996).
The World Health Organisation recommends a range of lower COHb concentrations of
2.5-3.0% as a standard for the protection of the general population, including those who
have impaired health. They have published tables relating time, ambient air CO ppm and
sedentary, light or physical work to COHb values (WHO, 1979). They have also published
exposure conditions to prevent COHb levels exceeding 2.5% - 3% in non-smoking
populations (eg CO TWA of 50ppm for periods of exposure not exceeding one hour).
Carbon monoxide levels from vehicle exhausts have been required to be reduced over the
past decade, as measured at warm idle, for environmental reasons (prior to 1986, 95% of
carbon monoxide in the air could be attributed to motor vehicle exhaust). The required
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
17
maximum levels have been 24.3g/km from July 1976 (ADR27A), 9.3 g/km from 1986 for
new passenger vehicles (ADR37-00) and 2.1 g/km for new models (ADR37-01) from 1997
and for all new passenger vehicles from 1998. In order to cope with the unleaded petrol
legally required since 1986 vehicles usually require catalytic converters (ADR37-00,
AS2877).
Testing involves analysing the volume of CO in the exhaust, over three drive cycles, and
then relating the resulting measure of parts per million to the distance covered, in order to
give a reading of g/km (Environment Protection Authority, Motor Vehicle Section, 1994).
3.3
MOTOR VEHICLE EXHAUST GAS
Motor vehicle exhaust CO levels vary from a cold to a warm start and according to the
presence or otherwise of a well-functioning catalytic converter. According to the EPA
typical late model vehicle exhaust CO readings range from above 45,000ppm (4.5%) at a
cold start to under 1,000ppm (0.1%) at warm idle. Older vehicles, especially those not
fitted with catalytic converters will show higher readings.
Morgen et al (1998), in Denmark, found that car exhaust CO levels ranged from an initial
proportion of greater than 9.5% in a car without a catalytic converter at a cold start to a
negligible quantity in a warm vehicle with a well-functioning catalytic converter. In the
vehicle cabin this corresponds to 6000 ppm soon after commencement, 3200 ppm after 30
minutes in the former vehicle without a catalytic converter and negligible quantities in the
latter vehicle (Morgen et al, 1998).
In a cold start situation, even with a well-functioning catalytic converter, death could occur
within 15 minutes. In a car without a catalytic converter and a warm or tepid start, death
could occur in one hour. In a warm start, with a well-functioning catalytic converter, no
toxic effect is likely to result from CO. CO2 and O2 depletion however may cause loss of
consciousness (Morgen et al, 1998). See recent work by Penney, 1998, Moller, 1998 and
Morgen et al, 1998 for further details on the interaction between CO, CO2 and O2 in the
exhaust suicide situation. It is of relevance that the rate at which exhaust gas
concentrations change in a space into which exhaust gas is emitted is dependant on the
concentration of CO in the exhaust stream, the speed and capacity of the engine and the
size of the enclosure into which the exhaust gas is collecting (Moller, 1998).
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MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
4.
MOTOR VEHICLE EXHAUST GAS SUICIDES – DATA
ANALYSIS AND OTHER STUDIES
The MVEGS rates for Australia in 1996 were calculated to be 4.73/100,000 males,
0.77/100,000 females and 2.72/100,000 total (National Injury Surveillance Unit, 1998).
4.1
DATA ANALYSIS
4.1.1
Australian Bureau of Statistics (ABS)
•
Australian MVEGS and motor vehicle registration rates were compared for the ABS
Motor Vehicle Census years since 1970. Since 1993 only new rather than total
registrations have been published by the ABS. Suicides show an increasing trend, with
dips in 1979 and 1993 (R2=0.58), while motor vehicle registrations follow an
exponential trend (R2=0.90), showing a steady rise (figure 7). Between 1979 and 1991
such suicides increased at a faster rate than motor vehicle registrations (Routley,
Ozanne-Smith, 1998).
Figure 7. Motor vehicle exhaust gas suicide and motor vehicle registration
rates, Australia. (1971-1996)
3
70000
60000
Motor Vehicle Registrations /100,000
2.5
2
40000
1.5
30000
1
20000
MVEG Suicides /100,000
50000
Motor Vehicle Registrations /100,000
0.5
MVEG Suicides /100,000
10000
0
1970
1973
1976
1979
1982
1985
1988
1991
1994
1997
0
2000
Year
(Source: Based on data from the Australian Institute for Suicide Research and Prevention and the
Australian Bureau of Statistics).
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
19
•
In 1995 there were 509 cases of motor vehicle exhaust gas suicides in Australia
(Attachment 1 represents 1 of 8 pages of case listings for Victoria 1993/94 only). This
was the highest frequency for which annual data is available. The number of cases has
increased by more than 400% since 1970 (figure 8). The most recent figure is 505
cases for 1996.
Figure 8. Motor vehicle exhaust gassings for Australia, 1970-1995
550
500
450
400
Numbers
350
300
250
200
Accidental
Suicidal
150
100
50
0
1970
1975
1980
1985
1990
1995
Year
(Source: based on data from the ABS, stationary vehicles only).
•
These 509 cases in 1995 represented 21.5% of suicide cases. Motor vehicle exhaust gas
suicide was the second most frequently used method of suicide. It ranked second to
hanging for men and third to poisoning and hanging for women. Since 1990 it has
represented approximately 20% of suicides p.a. (figure 5). Its most rapid rise was in the
1980’s.
•
The preference for this method varies between states (proportions of all suicides in
1994 by this method were highest in the Australian Capital Territory (39%) and
Western Australia (30%) and lowest in the Northern Territory (11%)) (ABS, 1995). It
appears to be a relatively favoured method in Australia compared with other countries
(eg 10% New Zealand (1994), 5.6% U.S (1991), 5% Norway, 2% The Netherlands
(1990-94)) (Langley, personal communication 1998; US National Center for Health
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MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
Statistics, 1996; Wiik, personal communication, 1998; Consumer Safety Institute,
Amsterdam, personal communication, 1997).
•
MVEG has been more favoured in middle age and by males. In the 30-50 year age
group MVEG has been the leading means of suicide and 82% of all motor vehicle
exhaust gas suicides were male. Numbers were substantial in the 20-24 age group, this
being the age group which has had the highest suicide frequency (ABS, 1995) (figures
9 and 10).
Figure 9. Exhaust gassings as a % of all suicides by age group.
%
30
25
20
15
10
5
0
0 -4
1 0 -1 4
2 0 -2 4
3 0 -3 4
4 0 -4 4
5 0 -5 4
6 0 -6 4
7 0 -7 4
8 0 -8 4
A g e g ro u p
(Source: based on ABS suicide data, 1994).
Figure 10. Exhaust gassing suicides Australia: frequency by age group
N
80
70
60
50
40
30
20
10
0
0 -4
1 0 -1 4
2 0 -2 4
3 0 -3 4
4 0 -4 4
5 0 -5 4
6 0 -6 4
7 0 -7 4
8 0 -8 4
Age
(Source: based on ABS suicide data, 1994).
•
There have been almost no suicides from CO in Australia other than from MVEG.
Unintentional deaths directly attributable to MVEG have been relatively rare in
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
21
Australia (figure 8), though higher rates are reported in the USA (figure 12), especially
in the colder states. The contribution of MVEG to driver fatigue and resulting vehicle
crashes is unknown in Australia - blood CO levels are not measured except in the case
of a vehicle fire. Also accidental poisonings from CO, generated by vehicles in motion,
cannot be separated from other causes of death within a broad category.
•
Hospital admissions for Australian motor vehicle exhaust gas suicide attempts have
increased steadily in recent years (1994/95 data are not available), with the data
showing an exponential trend (R2=0.99). Deaths also increased, but show no clear
trend (figure 11).
Figure 11. Deaths and hospital admissions for motor vehicle exhaust gas
suicides and suicide attempts, Australia, 1991-1996.
600
500
N (deaths)
400
300
200
Deaths
100
Hospital Admissions
0
1990
1991
1992
1993
1994
1995
1996
1997
Year
(Sources: ABS; Australian Institute of Health & Welfare, National Injury Surveillance Unit.
1994/95 data are not available).
4.1.2
Victorian Coroners Facilitation System (CFS) 1993/94
An analysis of the reasons given for the suicides, from the case narratives, are summarised
in Table 3. (See attachment 1 for examples of case narratives)
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MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
Table 3. Reasons for MVEG suicide, Victoria. (1993/1994)
Reason for suicide
Relationship breakdown
Depressed
Personality/psychological disorder
Medical condition
Financial problems, unemployed
Dispute
Death close friend/relative
Incest/rape/homosexual
Drinking problems
Other specified
Non-specified
Total
No. *
31
13
10
10
10
9
6
4
3
8
24
128
%
24
10
8
8
8
7
5
3
2
6
19
100
* There were 13 cases for whom 2 categories were noted and they have therefore been placed in
both of these categories. These were principally those of relationship breakdown and
financial/unemployed problems.
4.2
VICTORIAN CORONERS’ FILES
Case numbers of motor vehicle exhaust gas suicides undertaken in 1994 were obtained
from case listings in ‘Unnatural deaths’ 1993/94, State Coroner’s Office, Victoria, the
latest publication providing these details. Case numbers of 1995 and 1996 deaths were
provided from the Coroner’s Facilitation System database. Data on the practical details of
how MVEGS were undertaken, the type of hoses used etc were obtained from a sample of
thirty-three 1994 cases, thirty-three 1995 cases and thirty-four 1996 cases. The intention to
have the year of manufacture for 25 cases for each year determined the number of files
finally selected for examination. Twenty-five was considered a realistic number to
determine evidence of a trend, if present.
The year of manufacture, make and model were obtained for twenty-five each of 1994,
1995 and 1996 cases.
An investigation of a total sample of 100 MVEGS Victorian Coroner's files for the years
1994, 1995 and 1996 therefore revealed the results shown below. It should be noted that
not all case files provided information on each variable, so that totals may vary.
•
The 100 cases of exhaust gas suicide obtained from the records of the Victorian
Coroner comprised 33 of a total of 96 in 1994, 33 of 140 in 1995, and 34 of 136 in
1996. The year of manufacture had been recorded for only 75 of these cases (25 in each
of 1994, 1995 and 1996). Of these 75, 20% in 1994, 56% in 1995 and 32% in 1996
involved vehicles manufactured in 1986 or later. In total, 27 of the 75 vehicles (36%)
were 1986 models or later. This proportion is not significantly different (p=0.62) from
the 39% of vehicles in 1986 or later in the Victorian fleet of 2,799,310 vehicles in May
1995 (ABS Motor Vehicle Census) (Routley, Ozanne-Smith, 1998).
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
23
•
It is interesting that, at this early stage, of those vehicles fitted with catalytic
converters, there appears to be some variation in vehicle makes compared with their
representation in the Australian fleet. In the absence of comprehensive data this needs
further investigation.
•
In the 93 cases where the method was specified, all but 4 used a hose or pipe leading
into the interior of the vehicle with ventilation sealed. Twenty-two used a vacuum
hose, 17 used a garden hose, and 50 used another or an unspecified type of hose or
pipe. Tape of various kinds or cloth was most frequently used to secure the hose to the
vehicle. The hose most often entered the motor vehicle through the closest window and
the gap was sealed with tape or the window closed tightly onto a towel or clothing. The
4 cases not using a hose or pipe were in a closed garage.
•
The location of the vehicle in the 85 cases, where it was specified, was most frequently
at a home (51% cases), at an enclosed workplace (7%) or at an open-air location away
from home (including farm paddocks) (43%). A more detailed description is given in
Table 4.
Table 4. Deaths from Car Exhaust Gassings - Location
Location
Inside vehicle in:
-Garage
-Workplace (enclosed)
-Carport
-Home (outside)
-Bushland/parkland
-Roadside
-Paddock
-Car park
-Cemetery
Outside vehicle in garage
Total
No.
%
21
6
7
11
15
11
5
4
1
4
85
25
7
8
13
17
13
6
5
1
5
100%
Forty-six percent of the MVEGS were undertaken at the victim’s own home, 5% in another
home. There is possibly an indication here of why MVEG is a relatively popular method of
suicide in Australia. Australians have a high incidence of vehicle ownership and home
ownership combined with suburban living, often with garages to conceal a vehicle and
remote areas where MVEGS can be attempted undisturbed.
•
The engine was still running when the victim was found in two thirds of the 76 cases,
where this could be determined.
•
The median carboxyhaemoglobin level (COHb), for the 88 cases for which it was
noted, was 79%. The range was from 58% (no other drugs) to 95%. The measure,
however, is not necessarily regarded as accurate above 80% (Sugo,E, 1994). There
were lower levels (included in calculating the median) of 2%, 37% (combined with a
detected presence in the blood of paracetamol), 47% (with morphine and heroin), 49%
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MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
(with alcohol 0.18%) and 51% (with alcohol). In explanation of the 2%, a low level of
COHb in the blood does not exclude toxicity due to CO poisoning as the cause of death
if the clinical situation is strongly suggestive of it. It is possible that, by the time a
blood sample is taken, the CO may have been blown off from the lungs. Even if the
dose of CO is lethal, the person may not die immediately but continue to breathe long
enough to blow off the CO.
•
For the 75 cases in which both the victim’s COHb level and the age of the victim was
known, 26 involved vehicles manufactured in 1986 or later and 48 involved earlier
models. The median COHb level of victims in these two groups was identical (77.1%).
•
Information was collected on drugs detected in the autopsy. Alcohol was detected in 24
cases, benzodiazepines in 10, paracetamol in 8, cannabis in 7 and other
pharmaceuticals, usually in a ‘cocktail’ in 7. All of the above drugs and medications
were used in combination with others.
•
Hayward et al (1992) found that alcohol is immediately involved in 20 to 50% of
suicide cases in the Australian context and suggests that this involvement can be
viewed in two ways. 'Firstly, alcohol through its disinhibiting and depressant effects,
can contribute to the decision to suicide, which is often impulsive. Secondly alcohol
can be used for so-called “Dutch courage”, to facilitate the fatal action or to
anaesthetise against the discomfort of a slower form of death'. Similarly, the ingesting
of drugs has been implicated as a precipitating factor in suicidal actions (Hayward et
al, 1992)
•
Additional information was collected on age, sex and reasons given from the Coroner's
files for the sample of cases studied but the data reported on these factors has been
taken from more comprehensive sources - the ABS and the Coroner’s caselists.
•
There have been at least 2 cases of MVEGS in recent years resulting from asphyxia
from carbon dioxide identified by Victorian Coronial inquests. The technique used in
one case was as for CO poisoning from MVEG (hose from exhaust into the interior of
the motor vehicle). The victims’ vehicles had catalytic converters and Environment
Australia tests ‘at idle’ and ‘in drive’ measured no CO in the exhaust.
4.3
OTHER STUDIES
4.3.1
International Studies
Similar studies were undertaken in Sweden and Denmark.
• In East Denmark 228 medico-legal certificates from 1990 to 1993 were examined.
Similarly the MVEGS were predominantly male (88%) and middle-aged. The median
age was 49 for men and 46 for women. Sixty-five percent took place outdoors and
25% in garages (20% inside a closed vehicle, 5% outside the vehicle) (Thielade et al,
1998).
•
Ostrom et al in Sweden scrutinized necropsy, police and hospital records for 194
victims over a 4 year period. Again middle-aged males dominated. Most committed
suicide in a car outdoors by means of a vacuum cleaner hose. Suicide notes were found
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
25
in 40%. Severe disease, mostly psychiatric, was seen in 61% of victims. Blood alcohol
was detected in 51% of victims (Ostrom et al, 1996).
Studies completed in recent years in Australia which have provided useful information on
MVEGS deaths and hospital admissions are:
4.3.2
NSW Institute of Forensic Medicine
The Institute of Forensic Medicine in the N.S.W Department of Health undertook a study
Suicidal inhalation of CO - a reappraisal of variables affecting lethal levels involving the
investigation of NSW Coroner’s records for 112 vehicle exhaust gassing suicides over the
period 1991 to 1995. The study investigated the inter-relationship in suicidal CO fatalities
between COHb levels, exhaust characteristics, other toxicological findings and the
presence of natural disease processes which may affect the outcome.
The study concluded, inter alia, that there was no support for the view that current catalytic
converters (1986) are effective in reducing suicide by CO inhalation. Vehicles tested had a
mean 20g/km CO emission for non-catalyst equipped and 11.3g/km CO emission for
catalyst equipped. There was a small but not significant reduction in COHb levels for
persons using catalyst equipped vehicles. One fifth of vehicles were found to have catalytic
converters. The mean CO level was 72% (Sugo et al, 1996).
4.3.3
National Injury Surveillance Unit
Moller, from the National Injury Surveillance Unit, has also analysed ABS MVEGS data,
over the period 1990-92, and the following were of relevance.
The fall in suicide numbers in 1993 and 1994 was accompanied by a fall in the proportion
of MVEGS. This reflects the high lethality of MVEG, where a decrease in the use of this
means in suicide attempts is likely to result directly in a similar reduction in deaths.
If MVEG had been eliminated as a means of suicide since 1979, the upward trend in male
suicide would have been less marked and in female suicide would have remained relatively
constant.
There was little difference between urban, rural and remote regions in the rate of MVEGS
in the period 1990 to 1992.
Approximately 2% of MVEG self-harm hospitalisations result in death in hospital, and
about 70% of them require admission for less than 3 days with a mean length of stay of
about 6 days.
MVEG related self-harm represents a smaller proportion of hospitalised attempted suicides
(2%) than successful suicides (21.6%). This is likely to be the result of the lethality of
MVEG as a means of suicide compared to other means.
The age and sex distribution of MVEG related admissions is generally similar to that seen
for completed suicides. It appears however that younger males are relatively more common
among hospitalisations. This suggests that attempts among younger males are more likely
to be detected before death occurs presumably due to higher involvement of their family.
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MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
Of relevance here is a Chicago study by Maris (1981) who found that suicide completers
were much more likely than non-fatal attempters to be responded to by no-one, police
officers or firefighters, and much less likely to be responded to by family members or
friends. He considered that these factors clearly contributed to their suicide attempts being
fatal.
4.3.4
New et al, May 1996
The above author presented the results of the study on ‘Neurological Outcomes after
Carbon Monoxide Poisoning’ at the Royal Australasian College of Physicians Annual
Scientific meeting (May, 1996, Canberra). The researchers found four possible outcomes
in addition to death: delayed deterioration, progressive recovery, delayed recovery and
progressive deterioration. Increased risks were associated with extremes of age and preexisting circulatory diseases.
They noted that approximately 75% of patients progressively recovered with varying
degrees of residual deficits. Those who progressively deteriorated include those with
akinetic mutism and severe Parkinsonian features. In some studies up to 20% of patients
make a partial recovery but then experience a delayed deterioration between 1 and 6 weeks
after exposure. Case studies have also documented patients who make very little
improvement over many weeks despite treatment, but then experience a limited delayed
recovery up to 2 months after exposure. The varying patterns can probably be explained by
the heterogeneous nature of patients regarding poisoning severity, varying co-morbidities
and different treatment regimens.
4.3.5
Further Research
Greater knowledge of the aetiology of MVEGS could be gained from detailed data on
patients who have not ‘succeeded’ ie completed their suicide attempt. The reasons for the
choice of method, the duration of the attempt, why the suicide was not completed, details
of previous attempts and information on the make, model and year of manufacture of the
vehicle would provide most useful data. To date, studies focusing on the means of exhaust
gassings have been confined to deaths. Comparisons of completed and non-completed
cases may lead to the identification of further potential points of intervention.
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
27
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MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
5.
IMPACT ON EXHAUST GAS SUICIDES OF ENVIRONMENTAL
EMISSION CONTROLS
5.1
NATURE OF CONTROLS
Carbon monoxide levels from vehicle exhausts have been required to be reduced over the
past decade, as measured at warm idle, for environmental reasons (prior to 1986, 95% of
carbon monoxide in the air could be attributed to motor vehicle exhaust). The required
maximum levels have been 24.3g/km from July 1976 (ADR27A), 9.3 g/km from 1986 for
new passenger vehicles (ADR37-00) and 2.1 g/km for new models (ADR37-01) from 1997
and for all new passenger vehicles from 1998.
In order to cope with the unleaded petrol legally required since 1986 vehicles usually
require catalytic converters (ADR37-00, AS2877). These convert the harmful exhaust
pollutants of carbon monoxide, hydrocarbons and oxides of nitrogen into the relatively
harmless by-products of carbon dioxide and water.
The converter itself is a stainless steel canister that looks like a small muffler. It is usually
inserted into the exhaust system between the engine and the front muffler. The canister
consists of a ceramic honeycomb with a fine coating of alumina, containing platinum or
paladium metals to act as a catalyst. Harmful vehicle exhaust gases pass through the
converter, where the catalytic metals trigger the reaction of pollutants with each other. The
effectiveness of the CO converter depends on a number of factors including air:fuel
mixture which in modern vehicles is constantly monitored by sensors. The catalytic
converter does not work efficiently until warmed up. This usually takes about 100 to 200
seconds, longer in colder weather (EPA, March 1986).
5.2
IMPACT OF CONTROLS
5.2.1
Literature
The following is an example of case reports which have appeared in the international
literature attributing the victim’s recovery to a catalytic converter.
A 43 year old man was admitted to hospital in Britain after a MVEGS attempt in a SAAB
fitted with a catalytic converter. The engine had been running for about 5 hours when
discovered by police; he was semi-conscious. On arrival at hospital he was found to have
a COHb concentration of 21%. He made a good recovery , with no evidence of cognitive
impairment. Pre-catalytic converter, death would have been expected within 20-30
minutes. At this stage, COHb concentrations would be above 50-60%. CO controls,
requiring catalytic converters, have been in operation in the UK since Jan 1993, in
accordance with a European Community directive on standards for emissions (O’Brien &
Tarbuck, 1992).
Several overseas studies which have examined the relationship between suicides and
MVEG have found that the imposition of emission controls reduces MVEGS. For example,
Lester (1989) examined the changing rates of suicide by MVEG in men and women in the
US after the concentration of toxic gases were reduced in exhaust emissions. The
introduction of federal emission control standards in 1968 led to a considerable reduction
in the CO content of MVEG. This produced two measurable effects. First, the failed
suicide rate for CO poisoning increased (Hay and Bornstein, 1984). Second there was an
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
29
immediate decrease in the rates of successful suicide in men, and a delayed but reduced
rate among women. Curiously, the MVEGS rate for both males and females began to show
an upward trend again in the 1980's (Lester, 1989).
Further, Clarke and Lester (1987) compared the US and Britain in terms of their suicide
rates for MVEG emissions. As noted, the US introduced emission controls in 1968, whilst
Britain imposed no such controls. Suicides by MVEG subsequently declined in the USA,
whilst no decline was found in Britain. O'Brien and Tarbuck (1992) presented case-study
evidence in support of the introduction of controls on exhaust emissions in Britain
(introduced 1993).
However, if emission controls were clearly so effective, there would have been a decline in
MVEGS in Australia from 1986 and MVEGS would not be occurring in vehicles with
catalytic converters. The upward trend noted in the 1980’s in the USA is also puzzling.
One problem in assessing impact is that the availability of one method is unlikely to be the
only factor affecting national suicide rates. Information is relevant on the availability of
other methods for suicide, which typically are also changing at the same time. A
substituted method will need to satisfy many of Lester’s selection of method criteria. There
appears to be no obvious method to replace MVEG - perhaps drugs (which have a high
chance of recovery) or single vehicle crashes because they are vehicle related or hanging
because it an increasingly common method. National suicide rates are, as previously
mentioned, also affected by social and economic variables, such as the quality of life,
unemployment rates, marriage and divorce rates, and changing patterns of religious
behaviour (Lester, Abe, 1989).
Although the current and potential impact is not clear, some understanding can be gained
from the following:
5.2.2
Australian data
•
As shown in figures 5, 8 and 7 MVEGS have increased as percentage of suicides, rates
and absolute numbers, rather than reduced, since catalytic converters became
mandatory in 1986. In 1995, 43% of Australian motor vehicles were 1986 models or
later (ABS, Aug 1996). If catalytic converters and the 1986 emission standards of
9.3g/km had made MVEGS in post-1986 vehicles impossible, then MVEGS should
have reduced from 2.08 to about 1.19 per 100,000, between 1985 and 1995 (assuming a
similar distribution of vehicles to the Australian fleet and an unchanged number of
attempts). In fact, rates per 100,000 population have been about 2.5 for the past five
years and peaked at 2.85 in 1995.
•
Hospital admissions for MVEGS attempts in Australia have doubled between 1991/92
and 1995/96 (figure 11) (excluding 1994/95) suggesting some impact of lower toxicity,
resulting in hospital admission rather than death in some cases.
•
In an examination of 75 MVEGS Victorian files, where year of manufacture could be
determined, 27 (ie 36%) had catalytic converters.
5.2.3 USA Data
The CO environmental limits in the USA are below those for Australia. They were
9.3g/km in 1975 (associated with catalytic converters) (compared with 1986 in Australia)
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MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
and 2.1g/km in 1981 (compared with 1997 in Australia) (Code of Federal Regulations,
1997). The USA trends, therefore, should have some relevance to the Australian situation,
especially since the test conditions are similar. It should be noted that the average age of
vehicles is 7 years in the USA and 11 years in Australia, suggesting a longer lag time for
new vehicle exhaust emission changes to have an effect in Australia.
• Data from the USA shows a progressive increase in the number of MVEGS from 1981 to
1987, followed by an apparent decline to levels some 10% below the pre 1982 numbers
and rates. For accidental MVEG deaths there has been a progressive decline since 1978
(figure 12). The latest available year for USA MVEG data is 1991 (cf Australia 1996).
Figure 12. Motor vehicle exhaust deaths in the USA (1970-1991)
.
Motor Vehicle Exhaust Deaths in the USA (1970-1991)
2800
2600
2400
2200
MVEG Deaths
2000
1800
1600
1400
Accidental Deaths
1200
Suicides
1000
800
600
400
200
0
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
Year
(Source: graphed from US National Center for Health Statistics data)
•
Data from other sources show MVEGS in the U.S.A have reduced from 8.9% of
suicides in 1970 to 7.4% in 1980 and 5.6% in 1991 (Hay and Bornstein, 1984; Lester,
1996 ). The easy accessibility to firearms makes them by far the most common method.
•
According to Lester, the rates of men and women committing suicide by using MVEG
responded differently to the imposition of emission controls on cars. The male rate
dropped immediately after emission controls were imposed, whereas that of females
continued to rise. Eventually both rates dropped until the early 1980’s, whereupon they
began to rise again (Lester, 1989).
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
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•
Lester adjusted the number of cars for toxicity and found there was only a moderate fit
between exhaust suicides and the ‘toxicity’ of the total vehicle population (ie the
adjusted measure of cars in use). He interpreted these results as generally supporting
the potential for opportunity-reducing preventive measures, but also demonstrating that
much more research is needed into the complex nature of the opportunity structure for
suicide (Clarke & Lester, 1987).
•
In 1991, up to 56% of USA vehicles were post-1981 models (based on calculations
from registered numbers in the publication ‘World Road Statistics’). If the 1981
emission standards of 2.1g/km made suicide in these vehicles impossible, then
MVEGS should have reduced from 7.2% to about 3.1% (as a proportion of suicides
between 1981 and 1991 ignoring any impact from pre-1981 vehicles). The actual value
was 5.6%. This reduction assumes MVEGS have a similar distribution of vehicles to
the USA as a whole and the number of attempts is unchanged. A literature search
yielded no USA studies which investigated the age of vehicles used for MVEGS.
• Shelef noted that, after accounting for the growth in population and vehicle
registration, the yearly lives saved in accidents by MVEG in the US were
approximately 1200 in 1987 and avoided suicides approximately 1400. He attempted
to explain the unabated reduction in accidents compared with the MVEGS plateau
between 1981 and 1983 in suicides by the latter being a voluntary act and therefore
subject to many factors and that suicide can occur with “tricking” ie in a closed, sealed
space, a vehicle can be tricked into a richer mixture after prolonged idling (Schelef,
1994). However this will be an explanation only if suicides with the vehicle inside
closed garages rather than in the open are common (not so in Australia).
5.2.4
Japanese data
In 1975 the Japanese tightened emission controls (4.5% while the engine was idling) and
the accidental death rate from MVEG declined (Lester, Abe, 1991).
Ownership of cars continued to increase in Japan from 1950 to 1980, but emission controls
were gradually introduced in the 1970’s. The accidental death rate using MVEG peaked in
1970 and the suicide rate in 1981, at a time when this was the latest year of data. The
correlation between the 2 rates was 0.58 (Lester, Abe, 1990).
5.3
EXPLANATIONS FOR SUICIDES IN LATER MODEL VEHICLES
It appears that MVEGS have not reduced as much as expected with reductions in emission
levels and it is of note that the pattern between Australia, Japan and the USA may have
similarities ie a lagged levelling off after the introduction of CO exhaust limits.
Considerably less reductions are anticipated than would be expected if exhaust emission
CO levels of 2.1g/km made MVEGS extremely difficult to achieve.
In explanation, it appears that the testing for these legislated environmental limits may not
be particularly relevant to the suicide lethality situation where:
•
32
Α hose or pipe is led into the interior of the vehicle and ventilation is sealed. In this
situation, it appears inappropriate that CO limits are the same for each vehicle
regardless of the vehicle’s cabin volume.
MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
•
The engine idles. In environmental CO testing, there are 3 phases to the vehicle testing
and none of these involve idle only.
•
Other gases are involved (eg. oxygen depletion, CO2) which have a synergistic and
additive effect.
•
Heat and humidity buildup in the cabin may exacerbate the effects of CO.
•
CO from smoking may increase the level of CO in the cabin.
Situations where CO emissions may exceed the legislated limit are where:
•
The engine idles from a cold start, with a delay of between 1.5 and 3 minutes before
the catalytic converter has warmed up and is operating efficiently. Since
carboxyhaemoglobin concentration rises most rapidly when first exposed to CO, the
initial absorption rate would be particularly high (Ernsting & King, 1988).
•
Fuel vapours are purged from the catalytic converter when the vehicle is started.
•
Vehicles have a closed loop system ie an oxygen sensor controlling to an ideal air:fuel
ratio. A closed loop system may not operate at idle causing increased CO emissions.
•
Extensive idling after being driven may reduce the combustion temperature to a point
where the catalytic converter does not operate efficiently.
•
The air:fuel mixture of an idling vehicle is lean, causing the engine to operate roughly.
Adjustments may result in more CO being produced to make the engine operate more
smoothly.
•
The condition of the catalytic converter has deteriorated (eg. through being driven at
high speeds) or the engine may require tuning (under ADR 37-00 a catalytic converter
is required to operate effectively for 80,000km or 5 years, whichever occurs first).
•
Destruction of the exhaust system by the use of leaded gasoline, can increase the CO
content, and thus the lethality of this method for suicide (Lester, 1989).
•
The pollution performance has deteriorated. The pollution performance of 4-9 year old
cars has been found to deteriorate faster than older cars (FORS, 1996).
Additionally:
•
Modern vehicles may be better sealed ie less ventilation and modern exhaust systems
are made of less corrosive material and, therefore, are a more efficient director of CO
into the vehicle.
•
Cigarette smoking may provide an additional risk. It elevates the COHb by an average
of 2% per pack per day. It can be assumed that COHb levels while, or shortly after,
smoking would be higher than these average levels.
•
East Denmark researchers set up 3 vehicles (one without a catalytic converter, one with
a malfunctioning 3 way catalytic converter and one with a well-functioning 3 way
catalytic converter) to donate exhaust gases to a vehicle cabin under three different
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
33
starting conditions (cold, tepid and warm). Measurements of CO, CO2 and O2 were
made in both the cabin and exhaust pipe. A model was developed describing the
transient CO concentration in the vehicle cabin. They concluded that it is possible to
commit suicide by CO poisoning using a vehicle with a catalytic converter when the
engine is started cold or if the catalytic converter is not functioning well. They
considered it more difficult to successfully complete a suicide attempt using car
exhaust when the catalytic converter is well-functioning and the engine is started
warm. However, when the setup was very airtight, CO2 concentration high and oxygen
low, in the cabin, loss of consciousness and possibly death could occur (Morgen at al,
1998).
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MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
6.
PREVENTION, RECOMMENDATIONS AND PROGRESS
6.1
RATIONALE FOR PREVENTION
There are many examples to show that society believes in preventing suicide. For example,
$31 million has been allocated to the National Youth Suicide Prevention Strategy by the
Commonwealth Government over a 4 year period. Three hundred thousand dollars of this
is specifically for prevention of ‘access to the means’ (Commonwealth Department of ealth
and Family Services, 1997).
Society does, in various ways attempt to prevent suicide through particular methods eg in
prisons and youth training centres, prisoners cannot have belts, shoelaces etc. There is
some monitoring of favourite suicide locations and follow-up preventive action eg
monitoring of vehicles on the Westgate bridge in Melbourne and intervention when a
vehicle stops for too long; restriction of access to the roofs of high-rise public housing.
Also MVEGS victims are frequently physically healthy middle-aged men with dependents.
This issue should not, therefore, be confused with the euthanasia debate.
In order to justify changes to regulations, it is necessary to demonstrate the size and nature
of the problem which is to be overcome, the effectiveness of proposed solutions and the
likely benefits over costs.
6.2
COSTS AND BENEFITS
The cost of a road death was calculated to be $759,516 by the Bureau of Transport and
Communication Economics (Steadman and Bryan) updated to September 1996 by the
Consumer Price Index. Thus the cost per year attributable to 509 Australian car exhaust
poisoning deaths was approximately $386.6 million in 1996. This represents a cost of
$36.30 per year distributed over each of the 10.65 million motor vehicles in Australia
(Census 31st May 1995, excluding motorbikes, caravans, trailers; ABS). If a device were
developed which prevented 50% of these suicides and it cost $36, the full costs would be
recovered in just 2 years. Alternatively if a device cost $72, or if it prevented only 25% of
these suicides, the breakeven period would be 4 years. It seems likely that at least the
second of these scenarios could be achieved (based on costs and benefits in Routley,
1994). Furthermore, in this calculation the additional benefits of preventing several
hundred hospital admissions resulting from failed MVEGS are excluded. If the current US
Consumer Product Safety Commission cost of death figure of US$5 million were applied,
the benefits would even more quickly exceed the costs (ie in less than one year)
While it is considered that ultimately the solution should be in terms of performance
requirements for the vehicle, there are several design solutions possible for the prevention
(or minimisation) of MVEGS. These are intended to be neither prescriptive nor exhaustive.
6.3
DESIGN SOLUTIONS
6.3.1
Sensing Device
The mandatory incorporation into new vehicles of a multi-gas sensing device which
monitors carbon monoxide, oxygen and possibly carbon dioxide levels and, when levels
become toxic, displays a warning light, then emits an alarm and finally shuts down the
engine. The operation of window winding devices could also be incorporated.
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
35
Devices for the household which meet the Underwriters-Laboratory Inc. (UL) standard
2034 are available in the U.S for between AU$43 and AU$100 and a similar concept could
possibly be fitted to the engine management system of the motor vehicle. The U.S
Consumer Product Safety Commission recommends CO detectors which meet this
voluntary standard, UL 2034, the UL Standard for Safety for ‘Single and Multiple Station
CO Detectors’, April, 1993 edition, with revised requirements from October 1, 1995.
Detectors that meet UL 2034 measure both high CO concentrations over short periods of
time and low concentrations over long periods of time (CPSC Document #5010,
Underwriters Laboratories Inc., 2/4/96).
The U.S Consumer Product Safety Commission has been investigating technical
requirements to overcome sensitivity problems with currently available designs of CO
detectors. Potential tests include the use of chemicals (a chemical becomes darker in the
presence of CO and the alarm is activated by a light sensor), plug-in semi-conductors and
infra-red technology. Currently alarms are activated at CO levels which produce COHb
levels of 10% or above. They are not intended to alarm below 10% (Leyland, 1996,
personal communication). It should be noted that this is considerably above the 5% COHb
guideline of Australia’s National Occupational Health and Safety Commission.
The Recreational Vehicle Industry Association (RVIA) in the USA requires CO detectors
in motor homes made after September 1, 1993. RVIA requires CO detectors in all
recreational vehicles that are motorised. RVIA’s membership includes approximately 90%
of all US recreational vehicle manufacturers (US Consumer Product Safety Commission,
CO fact sheet, document 5010, 3/11/96). Such CO detectors appear to have relevance to
the MVEGS situation and warrant further investigation.
A multi-gas sensor could be incorporated with an anti-fatigue device or possibly an antitheft device, thus not drawing attention to its suicide prevention role (Moller, 1996). A
sensor attached to the engine management system of a motor vehicle would have the added
advantage of identifying and preventing unintentional CO poisonings and driver fatigue,
drowsiness and poor coordination due to oxygen deprivation and leaks of carbon monoxide
from unsealed boots, rusted holes and access through open windows. Recent research on
CO levels inside motor vehicles and on motorways has indicated the levels inside tunnels,
car parks and vehicles may approach 30 parts per million, which is the upper limit of what
is considered safe for the workplace over an 8-hour average. This level may be sufficient
to affect the ability of a smoker to think clearly (5% COHb level, compared with 2% nonsmoker).
The detection level should not be set so low, however, that the sensor would stop the
vehicle in peak hour traffic or cold underground car parks where carbon monoxide levels
are often high. The graph from Ernsting and King showing the relationship between time,
ambient CO levels and COHb levels (figure 6) and similar graphs, plotted by others, plus
those of CO2 and O2, are relevant to determine the correct setting.
6.3.2
Exhaust Modifications
The exhaust pipe on new vehicles and at the time of replacement could be modified to
incorporate a device inside the pipe, so a hose cannot be inserted, and to make the end of
the pipe irregular, to make it difficult to fit a hose. A model which incorporates current
design features is likely to be most acceptable - eg cross inserted and 2 oval-shaped pipes
immediately adjacent to each other (Attachment 2). If such a design or a performance
36
MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
standard were regulated for replacement parts, older exhausts would gradually be replaced
with the modified exhausts.
New designs would need to overcome any problems of backpressure, vibration or noise
and would need to meet current exhaust regulations (eg exhaust gases should be emitted
beyond the vehicle).
Since the average life of a rear muffler and tail pipe assembly is approximately 5 years,
about 50% of existing vehicles would have been retrofitted within this period.
A paper by Professor Peter Vulcan for the working party on ‘Reduction of Suicides –
vehicle exhaust systems’ provided a crude estimate of the likely effectiveness over time
and cost-effectiveness of carbon monoxide detectors and exhaust pipe modifications. The
calculation of such crude cost-effectiveness estimates is often done in considering future
motor vehicle safety measures as a guide to selection of the most promising approach.
Assumptions on the likely values of several factors were made, but if information or
opinion is provided which leads to a different value this can be substituted. The analysis
concluded that fitting a CO detection device to all new vehicles is likely to result in a
greater number of suicides being prevented ultimately than modification of the exhaust
tailpipe, at a similar cost per life saved, but with a slower rate of achieving the ultimate
result.
Both approaches showed sufficient promise of a potential cost-effective contribution to the
prevention of MVEG, to warrant further expenditure on research to better define what is
involved and to provide more precise estimated values for the assumptions made (Vulcan,
1997) (Attachment 3).
6.3.3
Further Improvements in Engine Design
Further improvements could be made in engine design and in catalytic conversion
techniques to complete the combustion process and thereby virtually eliminate carbon
monoxide emissions. Some vehicle makes are more advanced than others in this regard.
6.3.4
Other
Design possibilities, such as placing a potentially pungent odour in petrol to operate when
CO emissions are in heavy concentrations or oxygenating petroleum, could also be
explored.
6.3.5
Discussion
While there may be ways and means of circumventing these preventive measures, they
would require mechanical knowledge and planning and, therefore, more time for the
potential suicide to change his/her mind. Unlike safety and environmental design changes,
modifications to reduce suicide may need to be undertaken quietly ie without publicity or
media attention and possibly with the dual functions of another feature eg CO and O2
sensor for driver fatigue; anti-theft device.
It is of relevance that Ostrom et al concluded that environmental changes may reduce the
number of MVEGS eg introduction of a law requiring catalytic converters, of automatic
idling stop and of exhaust pipes incompatible with vacuum cleaner tubes. They stressed the
importance of appropriate treatment of psychiatric patients (Ostrom et al, 1996).
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
37
It is recognised that design changes will not eliminate all suicides. Complex social,
economic and psychological reasons underlie the causes of suicide and the solutions for
these require a multi-faceted longer term approach.
6.4
RECOMMENDATIONS
1. Mandatory regulations should be introduced for new vehicles which will make exhaust
gas suicide virtually impossible, by ensuring that life threatening levels of CO, O2 and
possibly CO2 cannot be reached by passing a hose from the exhaust into the vehicle
with sealed ventilation. A sensor is preferred because it would cater for deterioration in
catalytic converter and engine performance over time.
2. Regulations should be introduced for in-service vehicles requiring replacement exhaust
pipes to be of new safety designs to make it substantially more difficult to attach a
hose.
3. A study of MVEGS attempters (ie those admitted to hospital) should collect
information undertaken which further clarifies potential countermeasures and risk
factors. Variables on which it would be important to collect data are: how long the
vehicle ran, if they were interrupted, if they reneged, the reason for selection of the
MVEG method, the practical details of how they made the attempt, eg. equipment
used, the blood alcohol content and if possible the presence of other drugs, if they had
previously attempted suicide by exhaust gas or otherwise and information on the make,
model and year of manufacture of the vehicle. Such data would be most useful in
gaining further insight into how MVEGS are undertaken and the extent to which
catalytic converters are making an impact. Data collected so far has concentrated on
deaths.
4. The Suicide Module of the National Coronial Information System should collect
information encoded and/or in text including the make, model and year of manufacture
of the vehicle; COHb level; drugs, medications and other gases detected at pathology;
practical details of the attempt including equipment used; details of previous attempts.
Additionally there should be a move towards consistency in the medical and legal
definitions of suicide.
These actions should be undertaken quietly, without media attention. Adding to the risk
group’s knowledge of how to undertake this method, or risking ‘copycat’ suicides, should
be avoided.
6.5
PROGRESS
6.5.1
Department of Health and Family Services
The Australian Institute of Suicide Research and Prevention (AISRAP) produced a report
“Access to means of suicide by young Australians” for the “Access to Means” committee
of the Youth Suicide Prevention Advisory Group of the Department of Health and Family
Services and made recommendations for reducing access to the means of suicide including
exhaust gassing. The Mental Health Branch of the Department of Health & Family
38
MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
Services has responsibility for the allocation of $30,000 to conduct research into
alleviating exhaust gassing suicides.
6.5.2
Australian Medical Association (AMA)
There have been four meetings of a working group convened by the AMA, and initially the
Federal Office of Road Safety, to reduce vehicle exhaust gas suicides since November
1996, with representatives from various interest groups: automotive organisations - Federal
Chamber of Automotive Industry, Australian Automobile Association, Australian
Automotive Aftermarket Association, Australian Institute of Petroleum; government
bodies such as the Federal Office of Road Safety, Environment Australia, Health & Family
Services and the Australian Building Control Board; universities eg MUARC, AISRAP,
NISU and representatives from forensic medicine and psychiatry. The Secretariat has been
undertaken consecutively by the Federal Office of Road Safety, the AMA and the National
Road Transport Commission.
The initial meetings concentrated on becoming familiar with the issues and filling in
information gaps. The priority recommendations for the allocation of the H&FS $30,000
have been revised. These are now:
•
$6,000 to bring Prof David Penney, Director of Surgical Research and Professor of
Physiology, Wayne State University, US, an expert on the physiological effects of CO
to a meeting of the working group in Melbourne to determine an appropriate CO level
for a CO detector. He is expected to produce a report in September, 1998.
•
$15,000 to Dr Michaela Skopek of the Prince of Wales Hospital in Sydney to research
MVEGS attempters who have been treated for CO poisoning at the hospital’s
hyperbaric unit. The study is in progress and Dr Skopek is attempting to identify the
reasons for their method choice, their demographic profile, details of their psychiatric
record and any previous suicide attempts by MVEGS or other methods and the details
of their latest MVEGS attempt, including the presence or otherwise of catalytic
converters.
•
$5,000 to an industrial design student at the University of South Australia in Adelaide
to research the available exhaust pipe designs and to design a tailpipe which is low cost
(including fitting), which does not cause problems of backpressure or reduce
performance etc and which deters the fitting of a vacuum or garden hose. A design has
been produced which meets these criteria.
•
$4,000 for a computer model which simulates the exhaust gassing suicide scenario. Mr
Jerry Moller has now submitted a paper, which includes a model of CO and O2 exhaust
gas concentrations, to the Department of Health and Family Services Mental Health
Branch.
The AAA has allocated $15,000 to RMIT in Melbourne for the development of a CO
sensor for the vehicle cabin. Currently the emphasis is on developing CO, O2 and CO2
detectors. The focus will then be to link these into a multi-sensor system. Additional funds
are likely to be required for development to the next stage.
International enquires have produced very little activity to reduce suicides by this method
and it appears that this committee is leading the way internationally.
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Suicide,The Guildford Press, 1992.
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Moller,J, Motor vehicle exhaust related suicide and self-harm in Australia, paper presented
for FORS seminar, 1996.
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ATTACHMENT 3
Committee Draft
PAPER FOR AMA CONVENED WORKING GROUP TO REDUCE MOTOR
VEHICLE EXHAUST GAS SUICIDES
COST-EFFECTIVENESS OF VEHICLE EXHAUST GAS SUICIDE
COUNTERMEASURES
1.
INTRODUCTION
This paper attempts to provide a crude estimate of the likely effectiveness over time and
cost-effectiveness of two of the proposed countermeasures for exhaust gas suicides. The
calculation of such crude cost-effectiveness estimates is often done in considering future
motor vehicle safety measures as a guide to selection of the most promising approach. In
most cases it is extended to estimating benefit/cost ratios (but this may not be necessary
here if people do not wish to place a value on human life).
In making these estimates, assumptions on the likely values of several factors must be
made and these are stated. If information or opinion is provided which leads to a different
value, this can readily be substituted, or a range of values can be used (sensitivity
analysis).
2.
CARBON MONOXIDE DETECTORS
2.1
Background
Preliminary investigation indicates that it should be technically possible to design/develop
a CO detector that will sound an alarm and automatically shut off the engine when the CO
concentration inside the car reaches critical values. The critical values of CO
concentration are likely to be dependent on the period of exposure, being lower for longer
periods so that a critical level of carboxyhaemoglobin is not exceeded (see Figure 1). The
alarm can be set at lower CO levels for respective times than the engine shut off.
It is not known whether some of the new cars which more than meet the latest exhaust
emission standards would remain below the critical CO concentration/time envelope. The
proposed tests would determine this. A performance standard would enable new vehicles
to comply either by producing an engine/catalytic converter which complies with the
critical CO concentration/time envelope or by fitting the CO detector.
2.2
Performance Standard for CO Inside the Car
Once the critical CO concentration/time envelope has been determined, it would be
relatively easy to develop a performance standard that prevents the CO concentrations
exceeding these levels, e.g. along the lines of:
“When the exhaust gases are ducted into the passenger compartment with all windows and
vents sealed, the CO concentrations in the compartment shall not exceed the values shown
in Figure 1, at any time from cold start (e.g. after 12* hour storage at a temperature of
48
MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
2ºC*) until a full tank of fuel is used. The engine speed and manual choke (if any) should
be set at levels resulting in the highest CO concentrations for the first 60* minutes and then
at idling speed for the remainder of the time.
The horn of the vehicle shall be continuously activated when the CO concentration
reaches 90%* of the levels in Figure 1.”
Note: Figure 1 to be supplied by the working group on Project 1, but it will be based on
Figure 1 in this paper.
This type of performance standard would be suitable for new vehicles, provided that any
difficulties of a unique Australian requirement could be overcome. It may also be possible
to adapt it to vehicles already in use but installation is likely to be more expensive and
enforcement through State law could present some problems.
2.3
Likely Effectiveness
Assuming the device can be made tamper-proof for at least 95%* of persons attempting
suicide by this means and that the critical CO concentration/time requirements have been
chosen to protect at least 95%* of the population (there is likely to be a small percentage
with CO tolerance well below the average e.g. heavy smokers smoking at the time) then
the effectiveness in preventing a specific suicide attempt is 0.95 x 95% = 90% (at least).
An important unknown factor is the percentage (P) of persons who having failed in their
attempted suicide by motor vehicle exhaust gassing would be persuaded not to make
another attempt (using the same or a different method). The value of P is important to the
work of this committee, and attempts should be made to determine its likely value. It is
not unique to this countermeasure and needs to be estimated for all countermeasures.
Professor Pierre Baume has suggested that 40%* would be an appropriate value.
Hence the effectiveness in preventing all subsequent suicides by persons who chose motor
vehicle exhaust gas suicide is 0.90 x 40% = 36%.
2.4
Time Period for Implementation
If the standard was applied only to new cars, assuming the age of distribution of the car
fleet remains as at present, after 10 years only approximately 50% of cars would comply
and after 20 years the figure would be approximately 90%. A further 4-5 years should be
added to these figures to allow for development of the regulation and then lead time
between its promulgation and implementation.
If also required as a retro-fit, say as a condition of registration, the period to achieve
complete fitting could be determined, based on how long it would take to supply and
install approximately 9 million CO detector/engine disabling devices – say 2-3* years, with
a lead time of perhaps 1-2* years. Note this would be an expensive exercise, costing
perhaps $50-100* more than confining the requirement to new cars.
2.5
Number of Suicides Prevented
On the basis of 509 suicides each year using motor vehicle exhaust gas, when all cars have
P
been fitted, the annual number prevented would be 509 x 0.9 x
= 183, assuming P =
100
40%*.
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
49
However even after 20 years, only 90% of cars in the fleet would be fitted and it is
possible that some of those attempting suicide would search out the old (pre-fitting date)
cars. Hence it may be necessary to assume say 20%* of persons attempting suicide would
find cars not fitted even 20 years after fitting of new cars began.
Thus number prevented
183 x 0.8 = 146
During the first 20 years after the implementation of the new car requirement the numbers
in the first year would begin at approximately 201 of the above, progressively increasing by
a further
1
20
each year, thus averaging approximately half the above values, for these 20
years.
Retro-fitting of existing vehicles if it were feasible would achieve similar final numbers,
much more quickly, but at increased costs.
2.6
Cost of Implementation
It is difficult to estimate the cost of the CO detection/engine disabling device. If the
performance standard were a new vehicle requirement, after a reasonable lead time, it
could average approximately $60*. This figure is based on an assumption that some
vehicle manufacturers may be able to achieve compliance by developing very low CO
concentration exhaust even when starting from cold and hence may not need to fit a special
device.
Estimation for retro-fitting all vehicles is even more difficult, but it could well be in the
range of $100-160, say $130*, for fitting say 90% of cars (with the remaining 10% defying
the requirement).
2.7
Cost-effectiveness
When 90% of vehicles have been fitted the number of persons saved each year has been
estimated as 146.
For the new car requirement, assuming the present rate of 0.5 million new cars coming into
the fleet each year, the cost per annum = 500,000 x $60 = $30 million p.a.
Then after 20 years, when 90% of cars have been fitted,
cost effectiveness =
30,000,000
= $205,000 per life saved
146
and approximately double this value during the first 20 years of “build up”.
For retro-fitting, the initial cost of fitting 90% of 9 million vehicles is $130 x 9,000,000 x
0.9 = $1,053 million.
The benefits over the 20 years after fitting has been completed would be 20 x 146 lives
saved.
hence, cost effectiveness =
50
1,053,000,000
= $361,000 per life saved
20 x 146
MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
Note: These calculations have ignored the discounting of future benefits to present day
values, which economists would use to account for the fact that the vehicle device must be
paid for now, with benefits to accrue over the next 20 years. This would result in even
higher costs per life saved. They have also assumed that the devices have a 20 year life
and have ignored any maintenance costs for the devices during that period.
3.
EXHAUST PIPE MODIFICATIONS
3.1
Performance Standard
A performance standard could be developed to make it difficult if not impossible to fit a
hose to the end of the tailpipe. For example, it could be along the following lines.
“It shall not be possible for more than one person in ten* randomly selected persons
aged 15-60 years* to successfully attach within 20* minutes a hose selected from a
collection of standard hoses (say 4*) to the end of the tailpipe. The following tools
would be available to the persons: hammer, pliers, hacksaw, vice, sharp knife, etc.*”
“Successfully attach” could be defined as capturing more than 30% of the exhaust gas
flow.
3.2
Likely Effectiveness
The effectiveness of this countermeasure depends on what proportion of attempted suicides
could be completed without the use of a hose/piping.
Virginia Routley found that in a sample of 93 exhaust gas suicides, where the detailed
method was specified, all but four used a hose or piping leading into the interior of the
vehicle, with ventilation sealed. These four were in a garage with the doors closed.
However, the fact that these four suicides were completed, indicates that preventing use of
a hose/piping attached to the tailpipe will not prevent all suicides, if the car is in a garage
with the doors closed.
Further information on this may become available from the research projects being
planned. In the meantime, it is assumed that only 50%* of those who were unable to
“successfully attach” a hose would be able to complete suicide. This is a reasonable
assumption as in the sample examined by Routley, only 25% occurred in a garage.
The performance specification would require that at least 90% of persons would not be
able to attach successfully a hose to the tailpipe. Hence effectiveness in preventing a
specific suicide attempt using a hose/piping is approximately 90% x 50% = 45%.
Hence effectiveness in preventing all subsequent suicides by persons, who choose motor
vehicle exhaust gas suicide is 0.45 x P% = 0.18, where P is 40%*.
3.3
Time Period for Implementation
Mr. David Wright has advised that the frequency of car exhaust replacements varies
according to the age of the vehicle, as follows:
MOTOR VEHICLE GASSING SUICIDES IN AUSTRALIA: EPIDEMIOLOGY & PREVENTION
51
Pre-1985
passenger vehicles – average
2 years
1985-1990
passenger vehicles – average
5 years
1990-current
passenger vehicles – average
6-8 years
If fitting of the “hose resistant” tailpipe was required at the time of rear exhaust
replacement – through all replacement pipes meeting the performance standard then there
would be nearly 100% fitting within seven years.
Allowing say three years for the new standard to be formulated and implemented, the total
time for complete fitting would be 10 years from now.
The rate of fitting could be improved somewhat if at least the Australian car manufacturers
decided voluntarily that their tailpipes would meet the new standard (approximately 50%
of cars in the Australian fleet are less than ten years old).
3.4
Number of Suicides Prevented
On the basis of 509 suicides each year using motor vehicle exhaust gas, the number
prevented would be 509 x 0.18 = 92 per annum.
These values apply after seven years when almost the complete motor vehicle fleet has
been fitted. Over the first seven years of the introduction period the average savings will
be approximately half the above value.
3.5
Cost of Implementation
Given sufficient lead time and a guaranteed market, it is expected that a modified tailpipe
design could be produced for up to an additional $10*. This estimate could be refined after
some preliminary work on what type of design would be required to meet the performance
standard. Mr. Wright advises that there would also be a need to evaluate proposed designs
to ensure that they did not produce an unacceptable restriction to exhaust gas flow. The
proposed project to refine these costs is now required.
Based on an average exhaust pipe life of five* years and assuming the device must be
replaced whenever the exhaust pipe is replaced, the annual cost of the program would be
$ 105 = $2 per vehicle per year, i.e. $18 million p.a. for the fleet of nine million cars.
These costs would be proportionally reduced if the average life of exhaust pipes increased,
or the additional cost of the tail pipe modification were reduced or an “add-on” device
could be re-used when the tail pipe was replaced.
3.6
Cost-effectiveness
When all vehicles have been fitted, the estimated number of persons saved each year is 92
at a tailpipe replacement cost of $18 million per annum.
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MONASH UNIVERSITY ACCIDENT RESEARCH CENTRE
Hence, cost effectiveness is
$18,000,000
= $196,000 per life saved
92
This value would rank quite highly on a scale of cost per life saved by different
countermeasures. It also compares favourably with commonly used values of a human life
of $0.5 to 1.0 million.
During the first seven years, the average cost per life saved would be approximately twice
the above values.
Note: The benefits of prevention of hospitalised failed attempts have not been included in
these calculations.
4.
CONCLUSIONS
This set of crude estimates has shown that based on the assumptions made and set out in
each section, fitting of a CO detection device to all new vehicles is likely to result in:
(i) a somewhat greater number of suicides being prevented ultimately than modification
of the exhaust tailpipe (146 versus 92)
(ii) at similar cost per life saved ($205,000 versus $196,000)
(iii) but with a much slower rate of achieving the ultimate result (20 years versus 7 years
after the start of implementation)
The rate of fitting of the CO detection device could be accelerated by requiring retro-fitting
of the device to all vehicles over say three years, but the cost per life saved would be
considerably increased (e.g. $361,000 versus $205,000).
Both approaches show sufficient promise of a potential cost-effective contribution to the
prevention of motor vehicle exhaust gas suicide, to warrant further expenditure on research
to better define what is involved and to provide more precise estimated values for the
assumptions made in this paper.
5.
ACKNOWLEDGEMENTS
The comments on the action group on “Exhaust Pipe Modifications” - Jerry Moller,
Jeanette Pedlow and David Wright on an early draft of Section 3 are much appreciated.
The assistance of Virginia Routley in providing data and comments on this draft are also
greatly appreciated.
Peter Vulcan
Monash University Accident Research Centre
Fax (03) 9905 4363
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